The Dumb Joke Metric

If you go on a date, and you tell the following joke, and she laughs...she likes you.

A grasshopper walks into a bar and orders a beer.
The bartender says "You know, we've got a drink named after you."
The grasshopper says "There's a drink named Irving?"

Seriously, if you're not sure how the date is going, this is the way to find out.