Q: What happened to the beans when they showed up late to work?
A: They got canned!

Explanation: “To get canned” means to get fired, to lose your job.  Beans, when they are not fresh, come in cans (or are frozen).  Beans are canned when they are put into cans… but these beans were late to work so they got fired, they got canned!  This joke is funny because it plays with the idea of getting canned.