[dbloom]

Your microwave oven is likely a better choice, since its faraday cage-like behavior is required for both safety and regulatory reasons.

[xgbi]

And your key battery will thank you... Freezer would kill the battery in a few days of such treatment.

[dbloom]

Killing the battery isn't a bad idea either, actually :)

(Usually there's a recessed traditional key in the fob that you can use as a backup)

[vkjv]

Wow, I didn't think of it until I read your comment, but it would be super easy to add a switch to my fob!

With little more than a cap, you can throw on a button that enables the feature on for a period of time then disables it again.

[amenod]

Sure. Or maybe requiring to put a key in the lock! Oh wait...

[gaius]

... Unless you have a push button start...

[aidenn0]

Unlikely, assuming a lithium cell.

[amenod]

Be careful not to turn it on though (yes, there's a story behind that ;( ).