1 definition by Toastingurmom

The most extravagant reaction to something of funny, or toast-worthy nature, where someone uses their hand to make contact with their knee typically in a very absurd and flamboyant manner.
Guy: hey guess what
Guy#2: what?
Guy: UR MOM
Guy: performs a kneeslapper
by Toastingurmom February 27, 2018
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