Also a BMX trick
the act of sliding on/down a ledge/rail/block of any sort only on the back peg. Kind of like a bmx manual but you are on your peg, the friction can cause you to slam down and go over the bars, or if you try it on a rail you can miss and loose your teeth causing $16, 000 of dentist bills like my friend "halloween devin" as he is now known

check out this site for a pic
http://www.angelfire.com/vt/probmx/gallery/icepickgrind.html