Australian horseracing slang for the unexpected defeat of a hot favourite; a surprise result. Later used in contexts outside horseracing for an unexpected result in any context.
Bulgarian Tszvetana Pironkova, the world No.94, caused one of the biggest boilovers on Rod Laver Arena when she came from behind to record a 2-6 6-0 9-7 victory over Venus Williams.
by Quintius January 16, 2006
A dribbling orgasm instead of an explosion. Also experienced by old people.
After too many orgasms, the guy only had a boilover
by cartman197 September 15, 2006
When the fat on a woman (or man) doesn't just go over the edge of the jeans (as in muffintop), but spills down them as well.
You see that muffintop over there? No, Jim, she is most definitely a boilover.
by IrishPh3n0m March 1, 2012