Spying on my brother while he was masturbating. I did this for months while touching myself.
And going for a naked jog in a lonely forrest. While masturbating every mile or so. Of course I had the hope that someone would catch me. ;)

Amy's biggest taboo
 

back in the 90s we was at one of Amy's family reunion A bunch of us headed back to one of Amy's uncles house, now has the evening went on it ended up being me and Amy three of her male cousins her uncle and her dad there at the house. We was all drinking whiskey and as the whiskey ran out me and one of Amy's cousin headed up to the liquor store and 45 minutes later when we return we found all five of them in the bedroom and they was taking turns with her.

i suppose the most taboo thing i've done is on occasion playing "honeymoon" where her boyfriend and i bareback my wife in an attempt to seed .,..not that there's much risk at our age (late 40's early 50's) still for us it's a lot of fun to play let's make a baby during our threeway.

had a similar experience, but sandi was blindfolded & bound to a bench. Left there all our initiation night, I as taken to another room for my surprises - what a blast of an evening!

trucker fucker
 

.. maybe not the MOST but one of my favorites was advertising her on CL and getting replys from 2 truck drivers. Too large to pull into our neighborhood had them stop at a local gas station and the first (white redneck) called when he arrived. Took her to meet him and walked her through the parking lot in nothing but high heels. Hopped into his truck and she immediately started sucking him. Got in the back of the sleeper and he used her for 20 minutes until he shot his load all over her face and tits. During this time I was on the phone with trucker #2 who pulled in next to truck #1. She got out of the first truck and we hopped into the second (black young man).. again she went down on him for a bit then let him use her for another half hour or so until he too pulled out of her pussy and shot an enormous load on her face. Climbed out of the truck and walked her back to the car wearing nothing but the cum of two complete strangers. It was late so no one around but the cashiers but there were cars going by the highway. A fun time.

Mine
 

TOU Violation.

The Most Taboo Thing .......
 

It was letting my wife fuck an old university friend & roommate of mine. His name is Edwin and he established quiet a reputation with the ladies while there. Being we shared the same dorm it was natural to had see him naked once in awhile, usually going to/from the shower. His endowment was impressive even in its flaccid state. Anyway, after graduation we lost contact and it had been almost ten years since we last saw each other. We were both very surprised when my wife and I met up with him, just over three years ago, while she and I were on a combined vacation/convention trip. The second night there we all ended up back at our hotel suite after a night out on the town celebrating. As they say, the rest is history. Edwin got into Pam that night and gave her the fucking of her lifetime! The fact that he had almost 12 inches, and really thick, was indeed awesome, the fact that it was black was the jackpot! It was incredible watching him get that thing into her. I could never even fantasize of anything that big fitting into a pussy! It took awhile for him to stretch her pussy enough to take it all, but she eventually did, all the way to its equally impressive balls!

I smacked Obama's ass affectionately.

Krazy
 

I once had a situation where a Katrina victim that came to Philly had no where to go. Keep in mind she was hot as ever , ( 5"6 135lb Italian Spanish mix .) me and my wife were interested in a threesome , and my wife asked her and it was on . Me and my wife Did. A dp to her me and a strap , I pissed in her. Mouth and creampied her two times in both holes while my wife cleaned me off wit her mouth.

That's about as taboo as it gets....Becky:)