My dictionary says pump as a verb is to "operate like a pump". But when on is pumping one's fist, what does one do? I can't picture the action ...
Is 'fist pump' a common word or is it slang and (almost) nobody would understand me, if I used it? Could you give an example sentence? Is it possible to say 'to do a fist pump'?
What I read was something like "I pumped my fist". I think it's pretty common to say so.