when I was in junior high, my friends and I would joke about getting the "math class woody", where one would get an erection at very odd times without actually being sexually aroused. I'm 19 now and I still get them occasionally, however, and I was wondering if this is normal and also what causes this to happen.
I have a theory that it has something to do with being tense because it never happened in fun classes at school and when it happens now it is when I'm around my dad (who makes me very nervous) or around someone I'm uncomfortable around. It has the potential to be very embarassing!
I noticed that when it happens, there will be some other part of my body that is tense; like my leg, my shoulders, my neck, or I will be clenching my fists or my jaw.
thanks for taking the time to read this! I'm looking forward to what you have to say. 
Oh man the chalk talks!
Actually at 35 (next week) I still get the roaming chubbies and it doesn't matter what I'm doing or where I am. I can be driving down the road and up goes the tent... Talking on the phone and the elevator goes up. Thought guys grew out of this later in life but I guess 35 isn't late enough!
JR
LOL... Great topic. And yes, at the grand old age of 37, I still get the occasional HOFNAR (good acronym, Vagabondprince...lol). Hey, they're part of being a guy.
The only two storys I can think of relating to this... a guy in my high school senior class wore sweat pants to graduation practice... and obviously no underwear.... let's just say it looked like a boy scout's tent. And the WHOLE class saw it...lol.
The other really isn't a "hard-on" story, but I had a biology teacher who always wore black pants and- I don't know if he had jock itch or what- but must have always been scratching his crotch. You could tell because of the chalk patterns....lol.
aahahahahaha chalk prints can be very revealing... lol
hahaha. I dont remember ever doing anything like that in class...
I remember this one girl with fondle me under the dexk in Science class.... I mean yeah that guy is a total perv.. LOL
Ha this reminded me of my high school Biology teacher... he always seemed to get a hard on right at the beginning of class. Either he still got these random erections, or he was a total perv...
my friends and i used to call those HOFNARs (Hard Ons For No Apparent Reason). that's how common they are...they have an acronym. i think my body used to do it to me just to spite me. i'd get them right as the bus was pulling up to the school, i got them at the very last minute of english class in the ninth grade, and those are just the ones that happened every time, i'm sure i got plenty of others, but i think my body knew when i was going to stand up and would try to embarass me or something. i still get them, but not nearly as often now. lately i've been able to associate my hard ons with the presence of hot women in "scandalous*" clothing, and those are in abundant supply on my campus, particularly in the summer, god i miss the summer.
(*scandalous is a nick name a friend of mine has for clothing that accentuates attractive features on a woman, basically all skanky clothing is scandalous, but other attire can be scandalous as well)
Man i hate Random Hard Ons, it always happense when i am wearing like my PE shorts or board shorts... i think is connected with being nervous...
Well, it's been a long time since I was 19. I can't say that I remember the "math class woody" phenomena.
I wonder if it's a case of being bored or tense and almost unconciously escaping into some subtle pleasure?
I would have to say there are certainly worse things in life than a hard on and I don't think some random ones would cause me too much stress. I know I'm still amazed at how certain things (and people) can cause a twitch.