Boredom.

A brother and I get together (or try to) weekly and bring our special needs brother to lunch.  We've been going to a locally owned barbecue joint. 

This time our waitress was the owner's daughter and she mentioned how they were trying to figure out a good and inexpensive marketing idea.  Hello, you want me to brainstorm for you? Okay, try and keep up.

Apparently she didn't want us to brainstorm, she just wanted to whine.  We gave her I don't know how many low-cost/no-cost ideas and she was just bored. 

If you didn't want the ideas then don't ask for them.  Or at the very least you could pretend to be interested.