I eat nearly all of a fruit; like when I eat an apple or pear I eat the core, oranges/bananas/kiwi's I eat the peel (just not the stalk/end on a banana), watermelon's I eat the skin, etc. This tends to freak people out when I just chomp on an unpeeled banana.
When I'm talking to someone and explaining something, if they look like they haven't understood me or they've said something like "yeah I understand" but I think they haven't, then I'll repeat exactly what I've just said in a different way to try to get what I'm saying across to them (sometimes 3 or 4 times). This started happening about a 12~ years ago when I started managing staff, as I found they often just nodded and didn't get it, or looked like a deer in the headlights. This drives my current staff crazy, but I still do it
I guess a weird thing that I still do (but people don't know I'm doing it) is when I'm in the passenger seat on a car/train and I'm looking out the window, I'll imagine a computer game character outside jumping over cars, swinging around lamp posts, and bouncing on peoples heads - used to do it loads when I was young, kinda just kept doing it
mostly when I'm bored on a long trip.