…I realized I owned more dark socks than white socks. (2003)
…I first bought a CD by a band of guys noticeably younger than me. (Coheed and Cambria, 2005)
…I stopped being carded for alcohol, even at places like TGI Friday’s. (2005 or so)
How about you? Any more?
…the AAA man said to my son, “Who locked the keys in the car? Grandma?” and he meant me. I say it’s because I was with my sister who is 17 years younger than me, but I know the truth.
Someone you hadn’t considered all that young calls you “sir.”
Yes! Or persists in calling you “Mr. ________” after you’ve known them for a while.
When I noticed the sign that said “You must have been born on or before this date in 1982 to puchase tobacco products” and I realized I was out of high school on or before that date.
Recently, I realized that a close friend of mine was born AFTER that date. sigh
I was first called “Sir” at the age of 16, by someone who was probably much older than me. (He was selling tickets at St Pancras Station in London: presumably he addressed all male customers as “Sir”.)
When I realized that most of my co-workers were born after Star Wars was released.
When I looked at the doctors in the ICU caring for my boyfriend’s brother and thought “Dear Gods, how old are they?!” I’m only 31!
When you see vacation photos, and you laugh at the ridiculous, balding old fart on the left there – who is he anyway?
2006 - When I made a reference to a recent high school grad about Al Bundy and selling shoes, and he had never heard of the series.
2005 - My first real, bonafide grey chest hair
2001 - my first grey head hair, also the year I felt a snowflake hit my scalp, and not the hair above it.
1998 - Shortly before the Sheckstress, I dated a girl who was born in 1980. She didn’t know that tv used to come over the airwaves.
There’s a big one built into my job. I process these forms form incoming freshmen this time of year and they have the birth dates on them. This year’s group was born in 1989. I graduated from college in 1985.
When the centerfold in Playboy, the way you first found out what a nekkid woman even looked like, now has a birthdate subsequent to your graduation from college.
1985 - a person who had recently graduated from college said to me, “Wow - you were alive when Kennedy was killed!”
When I signed my life away on a mortgage
Mid '80s, when my sister asked me if Paul McCartney was in a group before Wings.
2001- when a kid came to work at the radio station. He had never seen a turntable before, and broke the stylus off the cartridge, scraping the tonearm across the record to find a track.
He’s my boss now.
It was 2003, I think—the year of the big blackout on the East Coast. I was living in New York City at the time and couldn’t get home because the subways were down. So, a coworker I always thought of as “a little younger” than me offered to let me stay at his place. Before your dirty minds start working, we’re both straight guys. He invited some of his pals over. So far, so good, but I was beginning to realize that I was a 31-year-old in an apartment full of 19- to 22-year-olds. The evening progressed, a lot of liquor was consumed, and I was feeling like my old college self. Then, in a moment that haunts me to this day, my hip, young coworker leaned over to me and quietly, politely asked, “Do you mind if we all smoke some pot?”
Do I mind? Hey, I’m a cool young guy. What makes you assume that I don’t want to smoke pot with you? OK, so I’ve never smoked pot, and I’m a complete dork. But I hadn’t previously realized that I was an adult.
That makes me laugh, and as a 33 year old myself, makes me cry a little inside. Great story. 
Welcome to the SDMB, by the way, Bayard. Hope you decide to stick around.
When some whippersnapper on the Straight Dope said “the year of the big blackout on the East Coast” and I thought “1964?”.
I’ll second all of that. Thanks, Bayard.
I nudged my son in Wal-Mart and muttered, “Check out the hottie!” and he looked at me quizzically and said, “Jessica’s mom?”
Hey, she *was * hot! Still is.