An old one, but a good one:

Our newest engineering mentor this season: "So let me get this straight. We have 6 weeks to design a robot, build it, wire it, program it, debug it, and then compete with it a few weeks later. ....... Are you sure it said 6 weeks? For my adult engineering projects, we have more like 6 months."

And of course our favorite new one:

"Why do I get the feeling that this is going to get me even less sleep?"