Wordwizard

1) He waits till he's onstage for his eyeball to explode.

Source:
Bill Maher
https://www.youtube.com/watch?v=ob7EWtaUL_o

From 3:15 to 3:20


I understand what he's saying and I suppose the context allows for a lot of licence. He is basically implying that Biden was responsible for what happened and there's no quick way to express that strange (and funny) idea.

But is the sentence really grammatical with the meaning Maher has in mind?

Once, during a debate one of Biden's eyes turned terribly red. That is what Maher is referring to. His eyeball seemed to have exploded. That happened when he was onstage. It could have happened at any time, but it happened when he was onstage. Now, Maher is jokingly implying that Biden is somehow responsible for that. And one readily understands his meaning. But I think the sentence cannot really be parsed

I do understand:
2) I waited till the concert was over for them to come out.
But that is different from '1', isn't it?

'1' is similar to:
3) I waited till everybody left to open the letter.

In '3' I am opening the letter.

'1' corresponds to the pattern:

X waited for Y to happen for Z to happen.


Gratefully,
Navi

As far as I see it, it's an example of a somewhat complex rhetorical device that is often used in English in which the causal relationship between an involuntary act and a person is blurred. The result is that the speaker appears to say that a person deliberately caused an event to happen, although no such causal relationship actually exists.

The technical term for this rhetorical device is "humour".

Thank you very much, Phil,

I think I've finally got it!!

By the way, sometimes one can be humourous jut by calling a thing by its name, especially if the thing in question is humour!!

Respectfully,
Navi