A fart with some anal contents (juicy, chunks...) that gets sprayed on your underware.
Dude 1: So there I was in line at the grocery store when I had to fart.
Dude 2: Ya?
Dude 1: Well, my fart was more than a fart...I got some sputter butter...my underware was so messed-up.
by RNPS December 15, 2007
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The expulsion of vaginal lubricant that often accompanies a queef, although the expulsion may occur for any number of other reasons such as: 1.) swift punch to the body (see donkey punch); 2.) bodily decomposition (see mung); or during a sit up occurring after feminine arousal.
1. Jess had sex with two men in one evening. By the time she was almost done with the second, she was queefing so bad that the butter sputter almost made Doug put on a rain coat for his own protection. The filthy act was wetter than a monsoon.

2. Not only did Luke's dog queef, but there was also some butter sputter, as evidenced by the stains in her dog bed.

3. The butter sputter left flecks of moisture on her panties, leaving her in an awkward situation as she sat on the church pew during mass.
by Jon - #1784 October 26, 2007
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