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1.
Remember that fat girl from last night? I was motorsubmarining her for hours.
by unearth December 27, 2011
 
2.
To tit-fuck the back fat of an overweight woman.
"Bill's wife is a really fat ugly bitch, huh? Look at those massive backboobs!"

"Yeah, but motorsubmarining is his fetish."
by DrPhilly December 27, 2011