Ok. I've got a few. I'll categorize these for convenience
Masturbation:
In 2nd grade I masturbated for the first time, in class. Teacher caught me twice because I was sitting right in front of her using a book to try to block her line of sight. I had to pee really bad, so I held my dick, got hard, and with minimal motion, it started to feel really good, so I just kept going. Had a solid 4 years or so of mess free masturbation after that.
9th grade I was again in class, watching a movie. *I bounce my legs when I sit in class* I got a boner and bounced my way to blowing my load in my jeans. Turned out to be a ghost jizz - I got up a half hour later to leave and there was nothing there.
Fall Junior year (college, this year) - Masturbate in a supply closet at my University's health services building while on the clock.
Spring Break Junior year - lost a drunken bet in PCB and spent 20 minutes in a room full of my friends (all guys) watching porn trying getting up, after which they took a pic of my erect penis and sent it to all of our lady friends in South Padre. Ended up not being able to finish because of whiskey dick.
Shitting
Sometime before it was totally unacceptable to shit yourself, but after it was okay, I went on a trip to Maine with my entire extended family. I was a kid where if I had to relieve myself but was doing something fun, I'd wait till the last possible second to run to the bathroom, and often it ended badly. We were exploring the tide pools and I had to shit, but they were SUPER awesome, so I ended up shitting myself. I was too embarrassed to tell anyone or change until after I had to shit again, and I ended up just going in my pants again. Horrified by embarrassment, I continued to shit myself for three (3) full days without changing or showering before my secret was discovered.
This year, again on spring break in PCB, I was playing civil war (fantastic game, look it up), and had to fart. I pushed to let it out, but three days of all Keystone diet meant I ended up dropping a small load straight through my shorts onto the floor of our hotel room. I waddled to the bathroom while everyone else took shelter on the balcony. Again, a picture of me cleaning it up was sent to all our lady friends.
Sex
Came out of blackout once in the middle of hooking up with a girl, I was naked and wondering why it was so hard for me to put it in her. I looked down to see she still had her panties on and I was just stabbing at them.
Having sex with my girlfriend in a shower at the Wisconsin Dells (standing doggy style). I looked down and saw her chocolate starfish looking back at me, and rationalized that if I were to put it in there, and she didn't like it, I could play it off like I just missed for a few thrusts and go back to vaginal. So I pulled out and poked her bum a few times but it didn't take, so I gave up and went back to the usual. She never knew it was on purpose.
Phew, thanks for being my personal therapist, NS. It feels good to get that all off my chest.
