How can I drop frames intentionally to test safeguards?

To preserve proper gameplay in the event of framerate jank, I've implemented various safeguards, such as movement stepping and all that jazz.

What's a good way to induce dropped frames in a controlled fashion, so I can test this? Ideally, I'd want to be able to say: If 'D' is Pressed: Drop the next 2 frames.

Then I can press 'D' before a critical moment in my game and see how well my game deals with it.

Any ideas?

You could use the repeat condition with a very high number.

fps wanks due to CPU or GPU choking. For CPU go with what Rojo said. For GFX i would use amped shaders

Very cool. Thanks for the ideas guys!