craftgrrl | Removing Iron-On Residue

Maybe I just wasn't looking in the right places in the memories, but I cannot seem to find anything that will help me figure out what I'm supposed to do.

Long story short: My boyfriend made me a shirt for my birthday - it was an inside joke thing.

He ironed-on three different letters (B-U-G), but told me he put them on crooked, so he ironed them off (without cleaning off the residue he left behind, of course) and then re-ironed them on.

So now, I have a shirt that has icky iron-on residue left on it, and I just want to know how to get it off.

Does Goo-Gone work? Do I need some kind of special fabric... stuff?
Thank you to anyone who has a suggestion!