It does look like it says "ASs." But it actually says ".45s" when you zoom in a bit (I'm using my phone screen).
Yeah ... I see.
And ol’ Billy Bob has no idea that the “.4” kinda looks like an “A” ... absolutely no clue that a “5” looks an awful lot like an “S”.
None whatsoever.
He’s totally innocent ... no crude double entendre there.
It’s a throwback vintage baseball cap referring to the original name of the Houston Astros. They were called the Houston Colt 45s for their first few years from 1962 onwards. They became the Astros when they moved into the Astrodome.