The art of spilling one's sexual mustard onto his thumb after a session of masturbation.
I ran out of tissues after I had a wank lastnight, I couldn't wipe off my thumb cum!!
by jackthehat June 29, 2011
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Verb

1. To merge two magazine pages together as one by means of bodily fluids.
"The fact that pages 136 & 137 were stuck together in the Hustler magazine at the sperm bank was an obvious indication that someone had been there cum thumbing it previously."
by billebllunt December 31, 2014
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