from an email conversation with Jean (just for a glimpse of what it's like in terrenceland):

Speaking of suicidal tiny plastic movie characters, I had a tiny plastic Slinky Dog sitting on top of my monitor at work. He'd sat there with no problems for about two years, then on the day Jim Varney (who did his voice in both Toy Story movies) died, he started taking dives off of my monitor. Seriously, he wouldn't sit up there for more than 10 minutes at a time that entire day without falling off. After that he sat there just fine. Creepy, no?

Needless to say, when Tiny Plastic Iron Giant started taking leaps off of my desk, I got worried about Vin. But he's okay. If Plastic!Spike ever starts doing that sort of thing, I'm liable to have a meltdown.