When you eat out someones asshole, and they fart in your face.
Last night when me and Samatha did it, she wanted me to give her a Smelly Nelly, it was so hot!
by Jakeypooandblackkid October 18, 2011
Private parts (either gender) with a particularly bad odour.
Don't go down on him, he has a smelly nelly!
by Meme Princess June 30, 2016