How many times do you feel it's acceptable to say "huh?" when you can't understand someone (either cos they're foreign or just have a heavy regional accent) before you just give up and pretending you understood? Maybe do some blank nodding an that too.

Who wants to carry on a dialogue of:
"The shmiiing poo ih cod."
"What?"
"Da shmiing poo ih cod!"
"What?!"
"DA SHMIIING POO IS CAWD!"
"WHAT!?"
"IT IS CAWD!"
"HUH?!"
If you haven't figured out what they are trying to say in one or two tries, the chances are that you are never going to get it. It's time to try a different approach. Always have patience - nothing constructive can happen if you loose it.
Me personally, I draw the line at about 3, but I really (deep down) wanna push it further. It's only some inbuilt sense of decorum that stops me, was hoping this place would tell me to man up an keep asking no matter what, but it seems the results are backing up the 1 - 3 ratio....
We're all pussies....
I know what Chuck Norris would vote
But if it's a teacher or my best friend or a parent and I get the feeling that they're saying something that I need to hear, I saying "what" as many times as I need to.
They usually give up after that. :)