Exlax

Leader: Give me an E!
Band: E!
Leader: Give me an X!
Band: X!
Leader: Give me an L!
Band: L!
Leader: Give me an A!
Band: A!
Leader: Give me an X!
Band: X!
Leader: What's that spell?
Band: EX-LAX!
Leader: What's it make you do?
Band: GO, GO, GO, GO, GO, GO, GO!

The rest of the cheer is done by the whole band/no one in particular:

Band: That's disgusting!
Someone (1): That's effective!
Someone (2): Next time, use Correctol!
Someone (3): Give me a C!
Band: No!
Someone (4): Give me an orrectol!?
Band: Hell No!
(optional) Someone (5): Evacuate! Evacuate! Rah Rah Rah!

This cheers is usually done when the Engineers are on the power play.