So this afternoon I went for it-- I found some frozen blueberries and raspberries in the fridge, added half a banana, and some milk, and whadayaknow I put it in a 12oz straw cup for him and he drank at least 3/4 of it. And this is just so awesome to realize, because while certain fruits he can't get enough of (strawberries, and just today he decided he likes blueberries again which he hasn't touched-- at least not in non-frozen form-- in months) most others he won't even bother trying. BUT! He'll probably drink them! (he's guzzled down my peach smoothie before but never dared taste an actual fresh peach) Not to mention getting him to also eat more greens (he does love green peas, and occasionally chows down on broccoli, but that's about it) and I'm seriously loving this idea.
(Of course, now the trick is to remember about this and actually make them for him... which, sadly, is harder than it sounds...)
You know what other frozen drink he likes to sip through a straw? Milkshakes. Specifically, In-N-Out milkshakes. We got In-N-Out a few times while Zach's brother, Andrew, was visiting a few weeks ago, at his request (sadly we don't go very often anymore since there isn't one that convenient to our home) and D showed a very strong preference for their shakes, specifically chocolate and vanilla ones (he didn't seem as keen on the strawberry for some reason). I kinda feel guilty sometimes for giving it to him since he drank enough for it to be a significant portion of his meal both times, but then again it's mostly ice cream which probably has more sugar but otherwise is not that different from the whole-milk yogurt we give him (and, it's not like we do that every day). Besides, he could probably use the extra calories... ; )