Does it mean "or else, you have to hire another postdoc"?
Lab equipment is expensive and delicate. And you, you’re not so coordinated. Nope. Not so much.
Oops! You could pay to replace this one broken piece, or you could hire another postdoc.
[not a teacher]
I think the humor is in Option #2, which might be implying that you will be the postdoc getting replaced, so be careful.