My most depressing? My 18th, I'd have to say.
Why? Because 5 - 6 weeks earlier, in an occupational accident at a car wash (that paid $1.25/hr), I got my foot caught in machinery (a bed of high-speed rollers) that ripped the flesh off the top of my foot, exposing muscles and tendons. I had to undergo multiple skin graft surgeries.
There was a young, married, secretary-receptionist on my hospital floor who had the morals of an alleycat. She'd sometimes drop by to chat, always in a tight blouse with a plunging neckline (she had quite an eyeful to show off), and "diss" her husband who'd gotten drafted to fight in Vietnam. Anyway, I digress -- She came in around 6:00AM one late October morning, at the start of her shift, to wish me a Happy Birthday -- while kissing me on either cheek, then fully on the lips.
What's so depressing about that? I was trying to stay "faithful" to my girl friend, Carol, who lived ~600 mi. away, in Minneapolis; so I quickly pulled away.
Sh**; I probably could have gotten a BBBJ on my 18th birthday, had I not been such a principled, naive, clueless dolt (I didn't even know there was such a thing as "oral")!
In the past year, I've done a damn good job of making up for the lost opportunities of my youth.
My best birthday -- I'd have to say my 57th, last year, when my ATF blew out my "candle"!