Buttstack or buttstacking- Requires atleast two girls-- When a girl's butt is laid ontop of another girl's butt, touching it, with both girls face down. Can be done more than once.
2) Man, you won't believe what happened yesterday night! I got these two bubble butt girls in a buttstack! It was -AWESOME-!
by Midorikawa Shun August 01, 2010