Yeah, your breaker box that's billed as 200A and has a 200A main breaker and wiring rated at 200A is quite safe. The breaker is designed to trip after a certain amount of time depending on RMS current, and the wiring is supposed to be able to tolerate that with some safety margin.
Your 40A (or whatever) oven isn't a 40A continuous load even on Thanksgiving. It'll draw 40A (maybe) while heating up, but it'll use much less while maintaining temperature.
If you really want, you can probably melt your breaker box, though. You'll need some really nasty nonlinear loads. Off the top of my head, with standard single-phase service, you want lots of even harmonics so that you draw 200A from each phase but put more like 400A on the neutral. Since your breaker doesn't sense neutral current, you won't trip it. (I suspect you'll acutally fry your utility's transformer long before you melt your breaker box, though -- most utilities use a rather different formula for transformer sizing and can't actually supply your rated current for very long.)
Your 40A (or whatever) oven isn't a 40A continuous load even on Thanksgiving. It'll draw 40A (maybe) while heating up, but it'll use much less while maintaining temperature.
If you really want, you can probably melt your breaker box, though. You'll need some really nasty nonlinear loads. Off the top of my head, with standard single-phase service, you want lots of even harmonics so that you draw 200A from each phase but put more like 400A on the neutral. Since your breaker doesn't sense neutral current, you won't trip it. (I suspect you'll acutally fry your utility's transformer long before you melt your breaker box, though -- most utilities use a rather different formula for transformer sizing and can't actually supply your rated current for very long.)