The sound made during a good, deep blowjob. It's the sound of sucking, choking, or gagging from having a big cock deep in the mouth. When the balls reach the lips, then you will here mphhhphh mphph mphphphhphhhhhh. This is onomateopoeia like a "meow" to a cat, or "oink" to a pig, or "slurp" to, well, a slut.
Amy: mphhhphh mphph mphphphhphhhhhh
MJ: Oh, yes! That feels great.
MJ: Hey, John, I saw your girlfriend last night.
John: Yeah? Where?
MJ: On her knees giving me the old mphhhphh mphph mphphphhphhhhhh
MJ: Oh, yes! That feels great.
MJ: Hey, John, I saw your girlfriend last night.
John: Yeah? Where?
MJ: On her knees giving me the old mphhhphh mphph mphphphhphhhhhh
by Pigslut Master March 16, 2008