Immediately after sitting in a booth for lunch at the local brewpub, my seat started shaking. I mentioned in a slightly elevated tone that someone had had way too much caffeine for breakfast, to no avail. When the waiter came by and asked if he could take our drink order, I mentioned that I was having a bit of trouble due to Mr. Happy Feet behind me shaking the table. The waiter looked perplexed, and said he would come back in a few minutes. I switched sides with my husband, who wasn't experiencing the same. After the food was served, this side of the booth was shaking. I couldn't enjoy eating because it felt like I was on one of those motel beds from the 70's with quarter slots.
Behind me the first time was a booth of 4 people in their mid-20s; the second one, a 60-something male (just to clarify that these weren't children).
Obviously, the booths should be more stable. They're tall, so you can't turn around to say something to the person behind you, but would have to get up.
What is a polite but effective way to ask someone to stop rattling the booth?
(if this has already been covered elsewhere, apologies!)