Its long form, "clack-a-lack," may also be used for special emphasis.
Rhymes with "gak," which, besides being an archaic Nickelodeon product, is a slang word for semen and/or ejaculating. Thus, to say "clack 'n gak" would be to suggest a "down and dirty" coital session in which the male only concerns himself with his own ejaculation and subsequent bragging rights.
May also be used to suggest any contact between two hard surfaces, usually instigated in an aggressive fashion.
"Dude, did you clack that shit?"
"Hell yeah I clacked it!"
Sounds much better than:
"Dude, did you clack her?"
"Hell yeah I clacked her!"
If the subject must be named in the sentence, then the pronoun "it" is still included and precedes the subject:
"Oh man, I'd love to clack it with the Olson twins."
Examples of non-sexual uses:
"Somebody tell this guy to scram before he gets clacked in the jaw."
"Damn, he clacked it out of the park!"
Mix of the words "classic" and "black" Used to refer to a man or woman portraying stereotypical African American behavior.
You: "Bro, stop being such a clack.