To take large amounts of some sort of drug, legal or illegal, usually in pill or powder form.
"My back was hurting so I took four 30mm codeine tablets."
"Mate, that's double the stated maximum dose! You don't wanna be boshing codeine like that!"
"I tell you what mate, my nose is right blocked up"
"Are you surprised? It's all that coke and speed you bosh every weekend!"
"Right lads, let's bosh these pills and have a ----ing bangingnight!"
Bosh its a method of describing a girl which provides oral sexual pleasure to different people simply because she likes to, it can also be used as the oral sexual act itself
1 she is a bosh/she gives oral sex 2 she gave me bosh/she gave me oral sex