A vaginal secretion of air (queef) of unfathomable magnitude. It is of too low of a frequency for human ears to hear, however it has been felt on a handful of occasions. The only known members of the animal kingdom known to be able hear muff thunder are Humpback Whales. Further research is being done as we speak
No, I was having really intense sex with Cindy and she let out some ridiculous muff thunder and rumbled my lamp off of the nightstand and it fell right on Simba's head.
by JKallday April 09, 2011