Here's a collection of goofy, fun, random idea generating exercises that you can always do when you're in a pinch!
Words from a Book
Grab a book and a pair of dice (or ask Google to roll the dice for you)
Repeat this process as many times as you want. It's a neat (and mindless) way to find interesting words that you can turn into titles, spin other ideas off of, or incorporate into a song.
Social Media Solution
Are you on social media? Do you have fans that follow you, or even a facebook page with your friends and family? Ask them to help you out:
You can repeat this process anytime you're looking for a challenge. It's a great way to flex your muscles as a songwriter, and to interact with your supporters.
Figures of Speech Web
Here's another one that calls for a pair of dice. Grab some dice and a notebook, and open up this webpage: http://idioms.thefreedictionary.com/
Or, you can just let The Idiomatic do it for you.