The act of fornication with both partners standing facing a wall. The partner directly facing the wall will then raise his/her legs and begin the tedious task of of climbing said wall while maintaining fornication and balance. Caution; the climbee must be very limber.
I gave your sister a Boston Wall Crawl until her feet were touching the ceiling! Good look getting those footprints down.
by Johny Dickrigger December 06, 2009