An old faithful is upper-decking taken to the next level. Here are the steps:

1) Remove lid from toilet
2) Flush toilet, then grab black floating ball in the tank before the bowl refills. Hold the ball there for now. The bowl of the toilet should be empty.
3) Fill the bowl up with vinegar
4) Pour about 5 boxes or baking soda into the tank
5) Release black ball, so the baking soda mixes with fresh water, and replace the lid. - leave, watch, and wait.

When the next user of the toilet takes a shit, the vinegar and baking soda mix to make what can only be described as a shit volcano.
I took a shit in my friend's toilet. When I flushed, it overflowed into a foamy brown mess all over the bathroom floor. It was then that I knew my friend was a victim of Old Faithful.
by moustacherocker July 26, 2006
Get the Old Faithful mug.
While a girl is fingering herself, she lifts her lower body in the air. Then, as she squirts, it looks like a geyser spraying up into the air. As the squirt juice falls back down, the girl then flails around with great passion as she is covered with her own squirt juice.
Guy: Why are you so sticky?
Girl: I just got done doing an Old Faithful.
Guy: What the fuck?
Girl: Yeah, I do it EVERY time I masturbate.
by Haywood Jablowmii September 6, 2012
Get the Old Faithful mug.
A ex-girlfriend or girl you can always depend on for sex when your feeling lonely.
Jimmy: Hey man I just got turned down by that hot girl at the club.
Bobby: No problem man, just call up your old faithful.
Jimmy: I didnt want to resort to that but sure, I really need some sex.
by daGangst4man September 8, 2008
Get the Old Faithful mug.
n.

1. The act of flatulating under the covers while in bed and spitting in the air so your significant other has to cover his or her face. Thus forcing them to bask in the ambiance. A variation of the dutch oven, just more sinister.

Footnote:
The victim of the Old Faithful is forced to choose between the lesser of the two evils: saliva or methane. It's win/win and %100 percent effective. Hence Old Faithful.
Last night my wife was complaining about me never talking to her after we have sex. So, I took a deep breath, let one slide, and gave her an Old Faithful. Needless to say we're separated now, but she had it coming.
by jason "jewboy" tracy July 31, 2006
Get the Old Faithful mug.
Named after the famous geyser in Yellowstone National Park, this is a schlong that spontaneously erupts and unleashes a cum geyser right into your girl's face when you pull your dick out of her mouth.
...And boy, was SHE surprised when she got sprayed in the face by Old Faithful!
by Mansnake February 11, 2005
Get the Old Faithful mug.
this is when the male ejaculates in or onto the anus of a female, she then farts and the jizz shoots up into the air, resembling the geyser, old faithful.
Jose: I got bored last night so i gave Jen the Old Faithful

Mike: Nice, ill test it out on Brittany
by Jack10392 May 6, 2010
Get the Old Faithful mug.