In The Beginning...
The secret language was only a way for the members of Phish to communicate to each other (what NothingLasts4ever calls "an intra-band signal"). They used the language a lot in the earliest days of the band's history (i.e. before 1990), and when it got to the point that entire songs were just made up of one signal after another, they decided to can it.
Phish being pretty silly guys, the ban didn't last long. They worked a few of the more amusing signals (the D'oh! signal; the Turn Around signal) back into a show every now and then. These signals were eventually noticed by hardcore phans who went to many shows, who began joining in on the ones they could, like the D'oh! signal. When the band realized this, they revealed some of the signals, and added some more just for the crowd during the second set of the March 6, 1992 show at the Music Hall in Portsmouth, NH, Trey explained the D'oh! signal (everyone yells "D'oh!"), the Random Note signal (everyone sings a random note), the Turn Around signal (everyone faces the back of the venue and yells "ow, fuck!") and the Fall Down signal (a new one; everyone falls to the floor or crouches). He explained a few more signals on March 11 (Campus Club, Providence, RI), including the Finger Scrape signal, and again on March 20 (Broome County Arena, Binghamton, NY) and March 28 (Variety Theater, Atlanta, GA).
Never having witnessed any use of the language myself, I can't offer you any first-hand experience. However, I used to have a guitar teacher named Adam who had been to a few Phish shows in the early 90s, who first told me about the language. Adam said at the first show he went to, the band immersed itself in this really slow, spacey jam, one to sort of lose your head in and all of a sudden, everyone in the crowd fell to the floor! Only he and his friend (it was his first Phish show too) were left standing. You'd think this signal would be used as a way to single out those who were 'uninitiated', but it was quite the opposite more than a few people approached him and his friend, and struck up a conversation about Phish, asking them how they heard about the band, what they liked, and also explaining the language to them.
The audience even took this to the next level, and invented their own signals/reactions to the band's songs. The first audience signal was at the November 13, 1994 show (Erie Warner Theatre, Erie, PA): the morning of the show, some phans got the idea to try to get the audience to do a tomahawk chop between sets. They hit Kinko's and ran off a couple hundred flyers explaining the idea, and handed them out as people walked in the door. And it worked on a recording of the show, you can hear the crowd singing the "aahhh" accompanying the tomahawk chop.
The next audience reaction was a flyer with three signals written up by Darius Zelkha for the December 8, 1995 show (CSU Convocation Center, Cleveland, OH): "If they play DIVIDED SKY, during the part where Trey is silent and stares at the ceiling, instead of yelling mindlessly, it would be really cool if everyone were to just SIT DOWN and quietly say 'ahhhhhhhhh....' [...] If they play WILSON, instead of chanting the standard 'Willllsonnnn', everyone should chant 'Cleeeeevelannnd.' [...] If they play STASH, instead of clapping twice during each drum break (which is standard), ONLY CLAP ONCE." It didn't go over so well, but Darius showed the flyer to Page after the show, who liked the idea.
Darius made up another flyer for the four Red Rocks 1996 shows (August 47, 1996). This one included the "Divided Sky" reaction from his first flyer, and added a reaction to "You Enjoy Myself" (echoing the lyrics after they're sung, like a round) and the now-standard "Harry Hood" reaction (yelling "Hood!" right after the band sings "Harry!"). It also said to get at least the whole front row (and preferably the whole crowd) to sing the first line to "Destiny Unbound" (Highway Bill's on a rotary still, and he can't even feel the pain), because Trey once said the only way they'd play that song again was if the front row sang that line. This time around, more people did the reaction and the "Harry Hood" reaction has grown to be standard. (The movement to bring back "Destiny Unbound" didn't completely die, either; it was done loud enough on August 16, 1998 at Lemonwheel to be picked up by the mics, but Trey just smiled and played the Beastie Boys' "Sabotage" instead.)
A reaction is standard with "Wilson" (chanting "Wiiill-sonnn" during the song's intro), but this is not an audience creation the song is from Trey's The Man Who Stepped Into Yesterday, which originally began with the pounding bassline and chant sung very high as an intro. The pounding bassline became an intro to "Wilson," and since the band wasn't singing the chant, the audience picked it up.
That said, the language hasn't grown much recently, as far as us phans know the band could still be using it and just not have told us...
Finally, for posterity's sake, a list tited "THE LANGUAGE," published in The Phish Book1 (verbatim):
- basic alert
- hi trill [actually part of the intro to the Vapors' "Turning Japanese"]
- tritone down
- ½ speed, speed up (2x speed f/tritone up)
- ½ step down
- go down ½, up whole, down ½
- Ambient B♭
- sing a note
- weep, weep, weep
- Waltz C♯ to G
- I let a song
- go to specified new song
- Get back
- return to 1st song of series, or prev.
- Sound of Silence
- silence (dont play on "1"), fake "blap"
- Will the Circle
- do cycle of fourths (at rate of signal)
- If it aint got swing
- "ah fuck!"
- Up Up Away, hi note
- start at top go down (arhythmic if hi note is vibrato)
- Up Up Away, lo note
- start at bottom go up
- raising ½ steps
- raising ½ steps / lo note
- ha, ha, ha, blap
- Me & My arrow: point at a person
- hi note
- tall person
- same note
- normal person
- lo note
- short person
- slo vibrato
- [no meaning given]
- fast vibrato
- [no meaning given]
- desc jerry
- asc jerry
- give them the finger
1: Richard Gehr, The Phish Book (Peripheral Books, 1998). The list is uncopyrighted.
Props to Phish.net for info on the audience signals.