1. A vulgar expression to depict the action of thrusting the penis into the vagina. Mainly used in the company of "Lads"; this phrase carries an air of Bravado about it.
2. Can also be used when describing a young lady who might not be up to ones usual standards aesthetically but would be adequate for the purposes of short-term sexual gratification.
3. Used in a jocular manner when performing everyday tasks. By simply emphasising the words, a very humorous effect can be achieved. ie When inserting a floppy disk into a computer.
"Stick it in, Derek!"
"I'd stick it in!"
"Have you been sticking it in?"
"You didn't stick it in did you?"
"Just take this disk and STICK IT IN!"
To stick an item usually a penis inside another's butt; commonly found in most imageboards, forums, public restroom walls, 4chan, etc., also usually accompanied with the picture of an angry japanese man shouting into a phone.
A: "I just met this girl recently, but I don't know what to do with her. What should I do?"