* You put Ketchup on a hotdog or hamburger bun (if you're a disgusting philistine)
* You could eat buns with a Fork.
* You shake your buns at a Dance.
The two food-related ones are most immediately apparent to me. That said, I'm not sure how else Lewwyn could have clued Dance and Ketchup, if those were the last remaining words. It's also possible that Dance was in fact a "tropical" word, and we just got lucky with nut or kiwi.
Although... I suppose "shake" would have clued Ketchup and Dance well enough.
Red looks to have gotten all of their words, so nothing much for us to analyze there. Seems they could have actually clued 5 for "clinic", since both words can be synonyms for "lesson".
1. KETCHUP is often put on a hamburger or other sandwich on a bun.
2. Buns are often served for a SCHOOL lunch.
3. Some people use a FORK to split their buns open because using a knife will smush them.
4. You can BOOT someone in the buns.
Lewwyn lives in China, so he might also be thinking along the lines of like pork buns. I think you're supposed to hold them with your hands or chopsticks, but a fork isn't too much a stretch of the imagination. That's how I eat them when I order from a Chinese restaurant or cook my own.
I've only heard of "buns" used as slang for "buttocks", but I guess he could be referencing bunions. Probably a better way to clue that and ketchup though, like "hock" or something, although ofc that doesn't mean it occurred to Lew.