Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

A teenage girl nervously asks her father if he could get her "some... protection" for senior prom night. The father calmly replies "Not a problem." The next panel, labeled "Later...," shows the father at prom pointing a shotgun at his daughter's date, yelling "You better use a condom tonight!" while the terrified boy responds "Okay! Okay!"

The joke plays on the double meaning of "protection." The daughter is euphemistically asking for condoms (contraceptive protection), which is already an awkward enough conversation. But the father interprets -- or deliberately reinterprets -- "protection" in the most stereotypically overprotective-dad way possible: physical intimidation with a firearm. The twist is that he ends up demanding the exact same outcome the daughter wanted (condom use), but achieves it through threat of violence rather than a normal parent-child conversation. It is a parody of the "overprotective father with a shotgun" trope, taken to its absurd logical endpoint where the father's aggression actually aligns perfectly with his daughter's original request.