Essentially it means smoking. Its just a slang term for it that you can say in front of authority figures without them catching on to what your actually doing.
(situation 1)
Ben- lets go smoke.
Kyle- yes im down to smoke right now.
(kyles mom overhears)
Kyles mom- you guys are fucked. no smoking.
(situation 2)
Ben- what do you wanna do today?
Kyle- Im down for some snoking.
(kyles mom sits by unaware while they go snoke)
The act of opening a friend/coworker/whatever’s browser on their computer and pulling up an image/website of choice while they aren’t looking, or are out of the room. However, this is typically done with a picture of a White Snake, hence the name. This is usually a harmless prank, but one can pull up lemonparty.org or the likes if they choose.