⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄ Auhm... The "preparation" thing... In reality.. Does male to male couple do that? Aaah so embarassing... ( ̄ε(# ̄)Σ
http://www.mangago.me/thing/about/17549/
An answer to all your questions.
In the end it's all about muscle contraction / muscle relaxation (the buttucks are our most prominent muscles after all) and various factors come into play in that departement: stress, consomption of psychoactive drug (including alcohol), experience, preparation, et cetera.




I knew it! I knew it!! NOOOooo!!! NO! NO! NO! NO! no! no! no! Ew ew ew ew ew eeew!!! (╬ ̄皿 ̄)凸
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What would be Sangwoo's excuse to Bum? #-.-) Blergh!!! YUCK!!!! Σ(  ̄□ ̄||)