I used to get beaten up by these green berets in my neighborhood. Some people call them Girl Scouts.

The line is a stand-up style joke built on misdirection. “Green berets” initially evokes elite U.S. Army Special Forces—tough, intimidating figures—so the claim of being “beaten up” by them sets up a macho, streetwise premise. The punchline flips the meaning: the “green berets” are actually Girl Scouts, whose green uniforms/berets are associated with wholesome childhood activities. The humor comes from deflating the speaker’s toughness and exaggerating childhood embarrassment, while also poking fun at the tendency to inflate one’s past hardships. It’s a compact example of Cotter’s self-deprecating, one-liner sensibility.