This was a pretty fun one. Got a good starting jolt with ACDC (1A: "Back in Black" band), then skipped over 5A: Biggest diamond?, and came right back with DESILU and THELORAX, the latter of which (14A: Title Seuss character who speaks for trees), I've only come to know lately through hearing about it in many different contexts. I don't remember ever reading this one (or having this one read to me) as a child.
I'm not sure what to call the theme today, but I chuckled at all of them. There is, however, one major problem, which I will soon address.
17A: "Wow, he survived!" - MANALIVE
26A: "Wow, you're a regular expert at turning left!" GEEWHIZ - now there's a word you don't hear very often, and I love its inclusion, but the main problem with this clue is that "gee" is used to turn animals to the right! It's opposite, "haw" is for turning left. Rather a glaring error, and one I'm sure Mr. Shortz will hear about. ("You'll say a better crossword editor has, maybe, sat a gee?")*
38A: "Wow, those reptiles have mad hops!" - LEAPINLIZARDS
52A: "Wow, look at that bovine idol!" - HOLYCOW
64A: "Wow, I'm standing next to Mr. Clooney himself!" - BYGEORGE
When I type them all out like that, it seems like rather a stupid theme, but I really did enjoy them while I was doing the puzzle. Of course, I was doing it at about 12:30AM, after having drunk a few beers, so my judgement could, I suppose, have been clouded.
Getting back to 5A: Biggest diamond?, the answer, ACE, was one of the more clever clues today. I liked seeing OMG (44A: Texter's expression of surprise) and having it cross DOH (42D: Homer Simpson's exclamation) was nice. I learned YENTA means (53D: Gossipy sort). I've never heard of GLENDA Jackson, but maybe in the future I'll remember that she's the 62A: Jackson with two Best Actress Oscars.
Aside from the major error, it was ok. Not great, but good and fun.
*I've since read that there is some confusion about this. Some say the meanings of the two words are reversed in Britain (because farmers sometimes walk(ed?) (does anyone still drive oxen thus?) on the right side of a yoked team, whereas American farmers, apparently, walk(ed?) on the left. The two words have consistent meaning (according to some sources I've read) relative to the farmer: "Gee" meaning "away from me [the farmer]" and "Haw" meaning "toward me"), but this is an American puzzle. Maybe they could've just clued it with "Wow, you're a regular expert at turning a draft animal!"