A female (or male) performs fellatio on a group of men consecutively, then immediately repeats the process in reverse order. Whomever goes last in the first round goes first in the second round, and so on. The name is derived from fantasy sports, where a 'snake-style draft' is conducted in the same fashion.
Person Two: Yeah let's put Mike last because he's a rapid reloader
Person Three: Snaking is when...
Bac: Man, I hate those snaking bastards.
Private: Uhh...he's probably snaking somewhere around here.
Dude 1: What have you been doing lately?
Dude 2: Uh....nothing. Just snaking all day.
I am so tired after eating, that I need a couple hours of snaking.
Shelven: "Oh Davis, what did you get up to?"
Davis: "Arghh we made passionate love"
"Shelven: Ohh you've been snaking Davis!
You slippery slimey Serpant"