Maybe Danny Zuko has to put so much grease in his hair to hide all the innuendos. Take this flirty exchange, for example.
RIZZO: What's up, Kenick?
KENICKIE: One guess.
Bow chicka bow bow.
If this movie were released today, it would probably be PG-13 for the sexual innuendos and its frank (for the time) depictions of teen sex. And considering how violent today's PG-13 movies are, the T-Birds might get into a rumble with real guns instead of water pistols.