Blow, but backwards. When you're toking, you would generally blow the smoke out. However, when a person milks a hit or just holds the smoke in and accidentally/purposefully 'swallows' the smoke, in about a minute or so after initially blowing smoke out, the person would let out a burp and voila, smoke that didn't leave when you thought youblew it out.
Francesca: Ay, puff puff pass.
Athena: ~~~milk the bolwz~~~~
Athena: *i'm gonna hold it in for a while, maybe taking a gulp will let me hold it in longer*
--blows out smoke--
Athena: I'm so --- *burp out smoke* -- the fuck? Hella just wolb'd.