Happy birthday indeed! Thanks for your puzzles, and even more thanks for your support of vulnerable youth. May this year, and all your years, be on the whole happy and rewarding, and may you continue to be a light for others.
If he had a nickel for every time he directed a movie involving tigers, he'd have two nickels (which isn't a lot, but it's weird that it happened twice)
11A
Not-so-formal affirmatives
12A
A rassler and a production company
14A
"I'm holding you to that!"
15A
How a politician may describe themselves when they're absolutely not going to be one ever
17A
Someone digging for gold
18A
Expensive beef options, usually
Down
1D
Bratty youngsters, or their diapers
2D
Need for some Rams
3D
Double- or triple-blind test, often; abbr.
4D
Feeling off after a workout [I mean gd knows I feel it whenever I think running 2 miles in 19 minutes is a good idea]
5D
Plopped a nickel you found on the asphalt outside a Shaw's Star Market into your personal stash, say
6D
The fancy name for some stirrups
7D
Pizza-focused food court chain I might treat myself to for my 9A
8D
Mussel which might have a cult based around it, for all I know
13D
One of two options for yaoi fanworks [For once I'm flagging this clue NSFW]