@aussieninja actually requested a self-insert cameo some years back and I think he was also the first person to do so. While I cheerfully made Ninjaroo for him, I was much less confident doing people as characters back then and as I'm better at 3d than drawing I decided to just jump straight to 3d for that one.
More recently I've been a lot more comfortable drawing people as characters (the terror of the person not liking the result is constant though) and inspired by one of his posts that included getting surprised by a dog on a run: