Top definition
An attempt during vaginal intercourse for one bro to secretly switch with another between thrusts. Thus the women has little to no idea that she is being railed by a different man.
"Catherine said you pounded her for over an hour last night! How did you do it?"

"Oh, my bro and I pulled a swap-in."

"Craig was doing this chick froggy style but starting passing out. Jon, unselfishly, swapped-in for him."
by swappers December 03, 2011
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