We are not talking about the high school prom.
If you have a date of birth, death, or marriage for an ancestor, you had to get it from somewhere. Sources should be cited. If the date is an approximation from an age at death, state so.
If birth date is an approximation based on the marriage date, indicate that.
Just don't drop dates in willy-nilly without a source.
And if you don't know where you got your prom date, well that's another story entirely.