I am a Purdue alum, although after the game last night, I am kind of ashamed to admit it J/K

Boiler up is said between passing PU fans, especially on game day. Although, the term is derived from the days of steam-powered locomotives, when the fireman got the fire in the coal box hot enough for the engine to run, he would exclaim "Boiler's up!"

We generally use it to mean 'man up' or take a drink