check her oil Share definition Flag When engaged in foreplay or intercourse you insert a finger or fingers into your partners anus, thus "checking her oil". "As I was doing my girl in the doggy position I reached down to check her oil." check her oil by Natedogg370 December 14, 2007 0 0 Get merch Get the check her oil mug. Buy Now — $32.95 See more merch
