Ahh, irony--what makest thou?

There was a debate among some of teenagers recently regarding what, exactly, constitutes irony.

I would like to clarify for all those who have any question: when we go to Lowe's and need them to cut a sheet of 4x8 plywood to size because the couple of bucks is worth not having to drag the table saw out at 8pm on a Sunday night, and they can't do it because their saw is broken, THAT's irony.