Gross, Grosse, und "Gross"

My children are learning German. They have friends who speak German so they are motivated.

There's a large church landmark in Zurich with two towers, called Gross Münster.

gus: It's called Gross Monster?
me: No, Gross Münster. Gross means "big" in German. Grosse means "large". Münster means "minister", or maybe "cathedral".
gus: So it means big cathedral?
me: Probably. I don't speak German, so...

Later...
sarah: Gus! You're gross!
gus: That means "big" in German, Sarah. You just called me "big".
sarah: Then, you're disgusting.
gus: Well, part of that is my name, Sarah... "gus" is in "disgusting".
sarah: Gus is short for disgusting.
gus: No, Sarah. Gus is short for August.
sarah: (flustered) rrrrrrrhhhh...