It means: Getting totally owned by a tank.
Except when you get the crap blown out of you by a long range tank shell. That's call tank n00bing.
Player: You call killing me only after 20 tank rounds? That, is called tank n00bing.
Tank Expert: 40-2. I totally panzored you all.
Troll: Shut the fuck up noob.
Player: Shut the fuck up troll.