Oh yes, the hovering hordes are a lot of fun, especially in their rush to pounce on your table. One guy even put down his tray over top of me as I went to stand, forcing me to sit down or wear his coke...so I said, "Sorry man, just doing a baseball adjustment. Not leaving yet. Sorry". And I pulled out my map and pretended like I was planning to go somewhere. 5 seconds longer and he'd have had the table...
Another time, we had this family that thought they could speed us up by peering over our shoulders and checking how much each of us had left to eat. I was getting pretty annoyed, and I am an extremely fast eater, so I finished well ahead of the rest of the group. While I was sitting there, I notice a father trying to balance a tray, push a stroller and keep a hold of his toddler. I felt for him, so I stood up, walked over to him and said (while winking) "Bob, there you are. We went ahead and started eating. I'm already done so you can take my seat. It's pretty crowded in here, but I'm sure everyone can fit." He got my drift pretty quickly, and I offered to push the stroller over. He sat down and the other family got cranky, but they didn't know any better. We played it cool until they left, he thanked us, and had a chat until the rest of my family was done.