here is my classification of farts:
The Thunderfart: the obvious, the rumbling loud one. A onomatopoetic translation would be something like "TR-R-R-R-RUMP". If you are seated, this fart vibrates down, through the furniture, and into the floor. It has an exiting power great enough to slightly widen the anus, the way a good solid turd does. I find this a _very_ satisfying fart, especially cus its airy and clean, and safe to push a little extra.
The "Oink": this is a shortened version of the thunderfart, it contains less gas, and is therefore less long lasting, and less rumbling, but still has a good and loud sound. This fart can also safely be pushed out, for more noise.
The sigh: this is the boring fart. i dislike these. theyre warm and stinky, and theyre no fun to fart. they just slide out of your ass without even trying to make a spectacle. the benefit, however, with this kind of fart, is that it draws less attention to you, if you can sneak out of the stink's way.
The "fake-foam-fart": my worst enemy. every since i was a kid, this fart will make me insecure about wether or not i have pooped myself. i haven't, but it never fails: it creates a wet and foamy sensation in the anus on exit, and often the wet foamy feeling remains in there. i have more than once gone off to check, just to be sure, and its all nice and dry down there.
these farts really mess me up.
The whistle: as the name implies, this one squeaks on its way out. i have only experienced this type of fart while pooping, so it must be something to do with how clenched your butt-cheeks are.
BONUS: the in-and-out-fart. this is a trick me and my brother tought ourselves as kids, and that we tought on to our friends later, this is how you do it:
lay down on your stomach, and poke your butt right into the air. now, in this position, your butt should be in a naturally opened stage - not spread - but not as clenched as when your walking or sitting. the clue is, you fart out, then do the "stop-peeing" muscle movement (both boys and girls have this muscle) and this will suck air back into your anus, so you can fart again and again. awesome fun for birthday parties, confirmations and bar-mitzwas.