Big fish, little fish, cardboard box

Preparation: Lean forward. Bend knees slightly, as if poised to run. Assume inane grin. When changing position, straighten knees and back in transit, causing the body to bob rhythmically.

Big fish: Hold hands in front of yourself at chest height, approximately shoulder width apart, fingers pointing forwards and palms facing one another, in a restrained version of the classic 'it was thiiiiiis big!' posture.

Little fish: Move the hands closer together, to about a distance of six inches.

Cardboard...: Hold hands parallel to body, one at chest height with the palm facing downwards and one six inches or so lower with the palm facing upwards.

...box: Resume the 'little fish' position.

Repeat ad infinitum, remembering to maintain at all times an expression of cheerful self-satisfaction at having Learned A Dance.

A kind of dancing, explained perfectly above, which goes equally well at both weddings and school discos. It was first brought to my attention by Johnny Vaughan on Channel 4's recently discontinued The Big Breakfast, as part of a sketch spoofing rave culture and happy hardcode.

To my mind, performers of the big fish, little fish, cardboard box dance should be accompanied by a shirtless man wearing raver pants beating 4-4 time on a big bass drum, and girls in fluffy moon boots with whistles and air horns.

If you're still not sure what it's all about, allow me to demonstrate...

      (1)  -  and  -  (2)  -  and  -  (3)  -  and  -  (4)

      ,,,             ,,,             ,,,             ,,,     
     (.. )           ( ..)           (.. )           ( ..)    
  ____\_/____       __\_/__         __\_/__         __\_/__   
 E___,   ,___B     /'_   _'\       (___M__,\       /'_   _'\  
     |   |         \__B E__/         | W___/       \__B E__/  
     |___|           |___|           |___|           |___|    
     | , |           | , |           | , |           | , |    
     | | |           | | |           | | |           | | |    
     | ) )           | ) )           | ) )           | ) )    
     |_|_|           |_|_|           |_|_|           |_|_|    
    (__|__)         (__|__)         (__|__)         (__|__)   

    BIG FISH      LITTLE FISH      CARDBOARD...       BOX     
 |<---------->|      |<->|    

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a scar faery adds that 'big fish...' is often accompanied by 'feed the birds, feed the worms' and others of its ilk, including 'dealing cards' and 'stacking shelves' if I recall correctly.
Stealth Munchkin informs me that the term was used in a comedy routine Michael Smiley used to do in about 1994.
IainB requested permission to use the ascii art on a t-shirt - go ahead, just let me know how it turns out.