When one has a flu accompanied by fever and tries to fart. The result is usually liquid poop filled underpants. The term is a combination of fever and shart.
Ryan was sick with a fever for days, and when he thought he was in the clear to let out a fart, he ended up fehrting himself.
"I thought I was over that flu, but when I tried to fart, I fehrted all over my self."
"I know. I can see the shit running into your socks."
by efube October 13, 2011
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