They're "off" when no one knows what's going to happen
13A
Approachable calculus concept?
14A
Pen pal?
16A
Normal-sized mermaid (seriously, I don't quite get what's so "little" about her)
17A
Chicago square (where they used to sell horse food? That name had to come from SOMEWHERE, I imagine)
19A
Place for a drive
20A
Specification in some Olympic events
21A
"I don't know much about French rivers... just ____"
22A
Huge-mouthed Nile swimmer
24A
Hard thing to do seamlessly?
26A
Wraps up
27A
What you have in Mario Kart when you get blue-shelled but stay in first place, for example
29A
It's not the same as a sweet potato
31A
March setting, for short
32A
"Who else could've done that?"
35A
Italian for "cooked" (so clay = cooked earth, #TheMoreYouKnow)
36A
Gran daughters
37A
Single-strand genetic material + enzyme suffix = certain enzyme that's the worst fill in the grid by far
41A
They may be hostile
44A
Drench
47A
Hut entrance?
48A
Noble one, somewhat redundantly?
49A
Journey such as Spock's
51A
Sticky black stuff
53A
Engrave?
54A
Breeze through a pop quiz
56A
Colorfully named bird
58A
Word before "sum"
60A
Making beds, say?
62A
Option near the top of a Word list
63A
"Incidentally..."
64A
Al ____ (just how I like my pasta)
65A
What perpetual motion machines make
66A
"THIS SIGN HAS SHARP ____. DO NOT TOUCH THE ____ OF THIS SIGN." (text on one of the most useless signs ever)
Down
1D
Hit yourself just because you like something, per a classic shower thought
2D
WWII Japanese emperor with a nearly reduplicative name
3D
"____ or ____?" (rhetorical question asked with confidence)
4D
Order from one aiming to lose weight
5D
City famous for its arch, for short
6D
Feel sore
7D
Some students' woes
8D
Ogles
9D
Slacker
10D
Letters that don't actually make the aspirated "h" sound
11D
____-quarter time (typical waltz tempo)
12D
"Would you be ____..."
15D
Strikes with claws, perhaps
18D
Word after "drug" or "Turing"
20D
Obstacle that works because swimming while wearing armor is basically impossible
23D
Nitpicker
25D
Sinatra's "My ___"
27D
Notable pen name
28D
"WORLD ____!" (first words uttered by a cockroach in a Fairly OddParents episode after he magically becomes super intelligent. Quite the ambitious goal but they got pretty close)
30D
One also known as a "Latter-day Saint"
33D
Salad ___
34D
Still locked off, perhaps
38D
Ticking off
39D
1994 sci-fi movie, or any of the warp portals featured in it
40D
It's got curves
42D
Battle or cattle expert
43D
Buzz's mate
44D
Dateless one
45D
Dangerous dolphins
46D
Look through a keyhole
50D
Young 'un
52D
Boardwalk has the highest ones
55D
Football supports
57D
Pulitzer winner found within "Teenage Euthanasia" (which is an actual title of an actual cartoon that actually exists, just why)
59D
Cries in Spanish?
61D
Dir. from Lake Hylia to Death Mountain in the Zelda Breath of the Wild map (take that, US geography clues that mean nothing to me)