I was hitting at my local park earlier today and a random player came up asking if I'd play a match with him. Naturally, I said yes. As we were warming up, he feeds the ball by letting it go and hitting it with the racquet before it bounces as oppose to a bounce-feed. That's cool, I didn't think anything of it, since that's how I feed too; I find that I can feed "nicer" and more accurately this way. Anyhow, once the match started, he served in this manner as well...Did I get aced? Definitely. That first serve caught me off guard since I was expecting a normal service motion, not a feed motion. He didn't ace me again after that, but he was very consistent with his serves and surprisingly has a lot of control on it. If I have to describe it in other words, it's like someone hitting a forehand from their shoulder height, that was how he was serving, tossing the ball to his shoulder height and kind of hit a forehand off of it. My tip? Expect the unexpected I guess.