Your dad was an asshole. And that story isn't funny at all.

We were all young and dumb at one point, hopefully the dad grew up. And the mom didn’t hold the son responsible

Or the dad's daughter (OP).

I went by the picture the op is a women

Yes it is!

Of course she didn't. Her son wasn't responsible for it. His girlfriend's dad was.

Well you can always say that you look like your mom, in every aspect

Your dad was apparently an asshole and it speaks to your character that you find his antics hilarious.

Your dad bullied, and probably psychologically scarred, some poor kid in a costume as his "senior prank."
Before calling something funny, put yourself in that situation. Would you like being in some bulky costume while someone spray paints you against your will? In a very public place, no less? If you wouldn't find it funny happening to you, think long and hard about yourself before calling it funny when it happens to someone else

That's the read you got from it? I thought the dad spray painted a picture of his own school's mascot on the surface of the football field of the boyfriend's mother's school.

You misunderstood the story.

Her dad snuck in at night and painted the image of his school’s mascot on the field of the mom’s high school. No people were assaulted. CTFD

Turns out the asshole gene is dominant.

There’s at least a 75% chance you’re going to make your boyfriend late to his mom’s funeral by wasting 15 minutes selecting a shirt.

It could be worse... by the end of the first sentence, I thought you were going to say that your boyfriend is also your half brother.

My dad’s senior prank was to steal a life size fake cow and tow it to his campus. He was caught and ended up spending the night in jail to scare him. THAT’S a funny story.

Keep it on the DL for now, lol

There's not a lot of exciting stuff happening in your area, is there?

Not really sure why he's an asshole...? I agree, it's not that funny, but it doesn't make him an asshole. Lol