I think that was a reference to the movie The Three Amigos. The characters misunderstanding the word sent them off on their unintentionally heroic adventure.
I had actually wondered if it could also just mean "famous" (but not necessarily in a bad way) like notorious can but apparently not. I had to look it up to be sure.
Definition of infamous
1: having a reputation of the worst kind : notoriously evil an infamous traitor
2: causing or bringing infamy : DISGRACEFUL an infamous crime
3: convicted of an offense bringing infamy