When having sex with a lady friend you insert you finger into her bum hole and wipe it under her nose (see dirty sanchez) Later on - During the love making - While french kissing your lady friend you wonder - "What is that smell ?"
I gave her a "Dirty Billy" last night and I can still smell it.
de Will Hiver 04 Februarie 2010
When you cum on the upper lip of your partner, extract pubic hair from yourself and apply it to them.
Since its movember, I'm gonna give my girlfriend a dirty billy today.
de mjens 14 Mai 2016