Many hilarious options of prank fart sprays are available on the market. The top brand name is Liquid Ass. You may have heard of this particular fart spray advertised and used on the Opie and Anthony show back in the day. I know that's when I first heard of it anyway.
Liquid Ass Prank Spray Bottle
The next step up from the classic whoopee cushion prank, the Liquid Ass brand fart spray allows you to create the aroma of a nasty gas leak instantly. It's quite simply just a fart in a bottle. This bottle is 30 ml of liquid fart smelling stuff, and it will last a long while considering it doesn't take much to work.
It is strong enough to make an instant impact and also has the added benefit of clearing away relatively quickly when the prank is done. Therefore, using this as a funny gag does not mean the stench will linger for a long time after the joke is over. Get more details about this and others by clicking the image of the bottle you see here.
Fart Spray and Fake Turd Combo Kit
Another stink spray option, is this fart spray. Shown here is another similar prank fart smell spray simply called Fart Spray. Another highly rated product. However, this one can also include a fake turd to complete the effect.
You will get a bottle of Fart Spray along with a fake, yet realistic looking piece of poo to lay around anywhere you want. The image here shows it being used on the side of a toilet to freak out the room mates.
Imagine all the hilarious places you could put this, along with a little spritz of the fart spray, then wait for the reaction.
Barfume Fake Puke Spray
If fake fart smells are not enough for you, you can also get other bodily function aromas, such as this puke smelling spray called Barfume.