Whilst going down on a lady, she suddenly and unexpectedly, latches her legs around your body and proceeds to barrel roll you, suffocating you. If this lady happens to be larger she is referred to as a "Bull gator".
This event typically happens in a swampy environment similar to Gainesville Florida, and is frequently performed outdoors.
Jimmy: "See that hottie I brought home last night?"
Doug: " Ya, more like a bull gator?!"
Jimmy: "She gave me an alligator mustache, and I blacked out."
Doug: "That's worse than a four locos!"