I love Pee-Wee's Big Adventure. I know the screenplay by heart. On command, I can recite the dialogue of the entire film from beginning to end.
The movie came out in 1985. I was 8 years old. The following scene practically documented a rhetorical technique popular among me and my peers - the "I know you are but what am I/Infinity" technique:
"I know you are, but what am I?" has devastating potential far above that of the more retrograde "I am rubber and you are glue" in that it invites the person against whom it is invoked to further mockery. Couched in terms of an existential crisis of identity - but what am I? - it is actually a blunt instrument of schoolyard verbal jujitsu.
Francis: You [Pee-Wee] are crazy.
Pee-Wee: I know you [Francis] are [crazy], but what am I [Pee-Wee]?
Francis: You [Pee-Wee] are a nerd.
Pee-Wee: I know you [Francis] are [a nerd], but what am I [Pee-Wee]?
Francis: You [Pee-Wee] are an idiot.
Pee-Wee: I know you [Francis] are [an idiot], but what am I [Pee-Wee]?
Francis, deemed through this interchange to be not only crazy but also a nerd and an idiot, changes tactics by employing "I know you are but what am I?" against Pee-Wee. After five repetitions of tandem volley of the phrase, the coup de grâce:
Now and forever, Pee-Wee knows that Francis is an idiot. Devastating.
"I know you are, but what am I" is, as previously stated, a blunt instrument. The invocation of "Infinity" is more of an art. How many tandem repetitions of "I know you are, but what am I?" should there be before the invocation of "Infinity"? There are no hard-and-fast rules, but surely after one or two repetitions "Infinity" would not be appropriate. Perhaps after three, under certain circumstances. The danger of waiting too long is that your opponent may validly invoke "infinity" before you do. Fortunately for Pee-Wee, his adversary seemed unaware of the "infinity" aspect of the "I know you are, but what am I?/Infinity" technique.
When I was eight years old, I rarely was that fortunate.