Nice wordplay! Leuke woordspeling! ^_^
Can I say "Ik ben boos" and can you say "Hij is boos op mij"? I only ask because it's complicated with prepositions to say this in German. "Ik ben boos op" is the only way for "I am mad at" right?
Yes to all of those questions.
'I am mad with my boss' is also a correct translation.
As an American, I would never say "mad with," but I would say "angry with."
When I was a kid "mad" only meant "insane", as in The Mad Hatter (he's not an angry hatter). Now, we've imported so much American television that "mad" primarily means "(very) angry" and "insane" is the secondary meaning.
But he could say mad at...
Kann mir jemand sagen was dann mad about means