When a TF2 Sniper crouches, looks up, and zooms in and out of their sniper rifle. Usually funny as fuck, even funnier when you do it when two snipers are fighting each other.
(Skype + snipe)
For one to run Skype and remain invisible, waiting for the appropriate target to change his/her status to online, and messaging them at that very moment.
I got an email today that was quite snifety. He commented that though the indivdual was very nice, he expected no help from them on the current project.