While Phelps competed on Sunday, his son Boomer stole the show from the sidelines. Phelps' fiancée Nicole Johnson gave birth to Boomer in May, thus immediately transforming the swimmer from just another hot Olympian to an indisputable DILF.
This prompted some people on Twitter to (accurately) remark on Phelps' DILF-iness.
For reference, here is some past photographic evidence of Phelps being a DILF in action:
It's official: Phelps now has a gold medal in DILF-iness! It's a real sport. Look it up.