Kill 3 aliens at once

Shoot down 20 alien fighters

Take steroids in SP

Knock out the talent at the talk show

Shoot down the blimp above the stadium

Find and steal a piece of poo

You were successfully promoted up a rank in multiplayer.

Play 100 notes in a single GH(tm)Jam session

Carry science forward

Reach rank 10 in Combat Training.

Detonate a HE Charge

Win any mission, whether campaign or What-If

Complete an objective after first selecting it on the Objective Wheel