I've thought a bit this week about the adage "don't trust anyone over 30."
The phrase "over 30" is ambiguous. Does it apply to people who are a single day over 30?
Or does it refer to people who are older in whole integers?
(After all, everyone who is 30 is already "over 30." And if 30-year-olds are not to be trusted, than the adage should have been "don't trust anyone over 29.")