Acceptable Targets: Shawn (and possibly the writers) has a vendetta against aloha shirts, and anyone who wears them whether they're a Hawaiian-Shirted Tourist or not. Possibly a Freudian Excuse because Shawn's father often wears them. The writers have a field day with it in "And Down the Stretch Comes Murder" :
Shawn: Wow, Dad, tell me you're wearing that shirt because someone has to spot you from space.
Shawn: A little girl outside just started crying when she saw this shirt.
Shawn: I'm worried someone's going to stare directly at the pattern and have a seizure.