So I was playing online with theDevilsiNME last night and we were doing the Hyperian Slaughter Dome ine Ore Chasm.
He was using his level 50 Zerker and I was using my level 50 Assassin and we were playing on normal so we were going through the enemies like a hot knife through butter.
After we finished I got on the lift to leave and as I got half way down the corridor "POP" Cheevo!
When I checked to see what it was, it had given me the Achievement for Gunzerking for 90 seconds even though I was playing as the Assassin. LOL