Why are Bladder Busters free?

When Bud/Doyle get out of Biodome they order pizza and Bladder Busters and when Russell (may he rest in peace) delivers the pizza and Bladder Busters he says "the bladder Busters are free because I couldn't find the place"

I don't get it. Why is it free? Because he took so long? I originally thought he didn't bring them therefore they are free, but he gives them Bladder Busters.

Therefore, the only logic I could come up with is that they are free because he couldn't find the bio dome in a timely manner. But that doesn't make much sense either since everyone knew where it was.

So, why are they free?