When a male ejaculates into his hand. He then proceeds to rub the semen onto the testicle hair and then runs the testicle hair over the woman's face. Hence, giving her the dirty paintbrush
I can't go out tonight... My wife wants to try the dirtypaintbrush and I can't turn it down!
When a man has anal sex with a woman, then uses the remaining excrement on his dick to paint on the woman's back.
Clarke: I brought Suz over last week and we got a little frisky.
JP: What'd you guys do?
Clarke: Well, I fucked her in the ass, then used the leftover shit on my dick to paint on her back. We called it the dirty paintbrush.
JP: That's fucking disgusting
A trip to a grocery store, convenience store, or gas station for the sole purpose of buying an excessive amount of junk food and sugary drinks, usually with friends. A chud run often happens late at night and ends with everyone involved hating themselves afterwards.