The wandering mongoose is not too different from a teabag or giving a mushroom stamp. There are two ways in which to perform the wandering mongoose, both of which can only be performed by men (im not sexist...you just need to have a dick for it.) Method 1 starts when you find or notice that a friend/roomate who has fallen asleep. You, simply enough, take out your dick and carefully balance above the victim-to-be. Drop down so your knees are on their arms, rendering them defenseless, and slap them silly with your dick. Proceed until they cry.
Method 2 can only occur when you're recieving a blow job, and you have to play it off very cool...casually grab some hair with one of your hands, then proceed just as in method 1. You probably don't want to pull this one if you ever want to receive a blow job from this girl again.
Guy 1-Hey, why was my sister so pissed at you last night?
Guy 2-Ah...yea dude, i showed her the wandering mongoose, and apparently she doesn't find it as funny as i do.
Guy 1-I swear if you don't shut the hell up, my wandering mongoose will attack you mercilessly in your sleep.