The act of engaging sexual intercourse while both parties involved keep their clothes on. Analogous to dry humping. Often performed when time factors into coitus.
I heard Ron was with Sally the other day, and they totally engaged in some serious zipper sparks.
by Captain Quigglebottoms March 8, 2011
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Zipper sparking refers to the act of dry humping while clothed.

Like dry humping it is the process of two people repeatedly rubbing their crotches on each other while fully clothed. Often achieving an orgasm.
"Oh man John wanted to zipper spark with susie so bad behind the bleachers at the Junior High School"
by JrMint September 27, 2004
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