Green’s Dictionary of Slang

can v.

1. [20C+] to stop doing something; esp. in imper., e.g. can that noise! [fig. ‘place it in a can’].

2. [20C+] (orig. US) to reject, to abandon, to discard, to dismiss from a job, to throw out, to ignore [toss out on one’s can n.1 (1b)].

3. [1910s+] (US) to put in prison; to lock up [can n.1 (4c)].

4. [1940s–70s] (US) to have anal sex with [can n.1 (1b)].

5. [1960s] (US black/drugs) to package heroin for sale [SE can or ? link to can n.1 (5)].

In phrases

can it (v.) [20C+] (orig. US)

1. to stop, esp. to stop talking; usu. in excl. can it!, shut up!

2. to reject or give up.