**Disclaimer** The following suggestions only worked for us when tried at the first sign of a possible impending meltdown, and even then not all the time. Unfortunately, we have yet to find anything that really helps once they are in full-blown meltdown mode, so prevention is key if at all possible.
One of our more successful "evasive maneuvers" to prevent a meltdown when we started to see signs that one was on the horizon, was to get silly. Extremely silly. Here are some examples:
Say a random phrase that they find funnyA couple of phrases that my twins made up are "stink the cat" and calling each other "cheeky belly." Don't ask me what either of these mean, I was never able to figure it out. But if I saw the storm clouds brewing, I could blurt out "stink the cat!" and suddenly they'd both be laughing, meltdown averted.
Deep pressure, deli style My sons loved it when I made "Bearhug Burritos" or "Cuddlebug Sandwiches." Basically, this is just wrapping them up or covering them in a blanket (depending on whether it's a burrito or a sandwich, lol) and then gently laying on top of them to apply all-over deep pressure. Of course, I added a lot of pretend munching and "yum, yum, yum! I just love [Bearhug] Burritos!" which usually made them laugh.
Random jokes Something along the lines of "You know what's funnier than twenty-four? Twenty-five!" (another Spongebob reference, lol).
Tickling You have to be careful with this one, because it can backfire and make them more upset rather than divert their attention to something funny. But, sometimes it worked for us.
Start counting or saying random numbers / letters / shapes (if your child likes numbers, letters, and/or shapes)
The idea is to catch them off guard and distract them from whatever it is that's upsetting them. Getting silly was sometimes helpful with Cuddlebug and Bearhug when it looked like they were close to the edge of a meltdown. Unfortunately, we haven't yet found much that helps with Little Bitty. Maybe some of these will work as he gets older? I'm definitely open to suggestions if you have ideas!