As far as I can tell, all of them.
I got my Ph.D. at age 40 (no, I wasn't in school that whole time), and began teaching.
Some of the boys in my classes would sit with their legs spread wide, unbutton a few buttons of their shirts to display some chest, drop by my office with little gifts like a can of soda, invite me to venues ("I'm singing at open mike night!").
Jostling for a higher grade? Maybe.
It wasn't just my own students. It was everywhere on campus. The guy who sold me yogurt at the student union, who checked out my books at the library, who worked out next to me in the gym.
I'm 54 now, older than the fathers of most of the boys, but the cruising continues unabated.
He was cute above the belt, too: rather short, with curly black hair, brown eyes, a square jaw, and a solid physique.
A few days later, at brunch, Scott was our waiter! I told him I was a professor at the college, praised his acting talent, and claimed to be his biggest fan.
The next week, we went out to breakfast again at the same time, and made a point of getting Scott as our waiter. When I paid with a credit card, he said "Could I check your id, Professor?"
No one ever calls college professors "Professor." It felt weird. But I handed him my driver's license. "Ok, you have my height and weight," I said. "What other measurement would you like?"
Scott laughed and handed my driver's license back.
I went home and friended him on Facebook. His timeline and personal information didn't give a clue about whether he was gay or straight. But mine did.
He talked about growing up in a small town in Minnesota, feeling "different," and finding a safe haven in theater, and I told him my best "dating a celebrity" stories.
He wasn't impressed by Michael J. Fox, Cesar Romero, or Richard Dreyfuss. But Andrew Lloyd Webber! "What was he like? Did you do anything? Was he hot? Do you have his phone number?"
After coffee and listening to a weird local band, Scott invited himself back to my apartment, a few blocks up the hill. I was going to show him my collection of classic musicals on DVD, pop in On the Town, and then make a move, but the moment we walked in the door, he pounced. Before I knew it, we were rolling around on the living room floor, and he was moaning "Take me, Professor! Use me!"
Ok -- my name is not "professor." This isn't Gilligan's Island.
He was done before I even got his pants off.
"Sorry, Boomer...this has been a fantasy of mine for a long time."
He was willing to stick around for a bit, but still....
The next night, we had dinner at the Indian place downtown.
We returned to the apartment and sat on the couch to watch Chicago. But we didn't make it far into the first scene. Suddenly Scott was on my lap, kissing and groping me and moaning "Punish me, Professor! I've been bad!"
Obligingly, we all went into the bedroom and took off our clothes. Scott had a nicely muscled, slightly hairy chest and a nicely shaped Bratwurst.
"I want to spend all night with you, Professor..."
"Sorry...um... Boomer. I want to try everything with you!"
"Let's start by getting into bed."
I took him into the bedroom. Instantly Scott was on top of me again, groping, whispering "Could we do it in your office, Professor? Pretend I'm failing class, and I have to do something to pass."
"I don't do anything on campus," I said. "That's inappropriate. And call me Boomer."
But he wasn't paying attention. He was lost again in his fantasy world. "Professor, tell me I've been bad, and you're going to punish me. Keep me after school. Spank me with your belt. Make me cry..."
And he was finished.
I invited him over for a "special evening." I draped the bedroom in black, put black sheets on the bed, and borrowed a lot of S&M equipment from a friend: black-painted rope, handcuffs, clothespins, three whips, a paddle, a ball-gag, a blindfold, and four dildos (including one too big to actually use on anyone). Chaps and a leather vest completed the scenario.
When Scott came to the door, I brandished the whip and said "You're late! I don't abide tardiness!"
"There was traffic." he said, staring, annoyed. "Chill."
"Um...come into the dungeon for your punishment." I took him by the arm and dragged him into the bedroom.
He stared at the equipment. "Um...hey, I'm not into pain, Or toys. Or getting tied up. Couldn't we just do...you know..kissing, oral, regular stuff?"
How embarrassing! "Sure, ok. Let me just get out of these chaps."
"Let me help you out of them." A moment later, we were rolling on the bed, and Scott was murmuring "Take me...use me...punish, me, Professor!"
By the way, with Scott, I surpassed my age gap record. He was 32 years younger than me!
See also: The High School Bodybuilder; The Hookup Contest Part 2, and Our Date with the Teenage Beach Boy.