Good ol' fashioned guilt

So I have someone trying to guilt-trip me into doing something neither M nor I want to do. The guilt is coming fast and furious, and I am pissed. I fired back at this person, but now I feel bad. Growing up Catholic, the guilt is something I am heartily used to. But I hate it, and I've never really learned how to deal with it.

So how do you deal with guilt trips? Ignore the person? Get nasty? Put in a guilt trip of your own? Tell me your story.