Cervical bruising is every bit as painful as it sounds, guys. Think about it - would you like to be poked 100+ times in your tender spots with a hard object? To make it worse, guys who pride themselves on length inevitabily seem to think that “lasting” is a feature women want in sex.
I can stick my index finger - all three inches of it - inside and feel my cervix, most women can - it doesn’t take much in terms of length.
http://www.unpopart.org/texts/firstblowjob.html
Old National Lampoon article.
*There, plainly revealed in the green fluorescent glow of the “Apex” sign, Connie saw Jeff’s tan, athletic penis straining toward her. *
Can you say that a little slower? Hold on a second, let me put on some mood music.
Bigger isn’t better, unless you mean “better for staring at and wondering if it’s too late to suggest simply watching a movie.”
Gay male, typically bottom checking in. My experience has been that while I appreciate girthier penises, if a penis is too long it causes me more discomfort, as long as the guy with the thick penis spends some time getting me ready for it, so to speak. If I had to put some numbers on it, I’d say 6.5-7" length, and 1.75-2" diameter as a rough starting place.
I think length is very critical. It’s really easy to be WAY TOO PAINFULLY LONG. I don’t want a guy with a longer-than-average penis anywhere near my girlie bits, thank you! That freakin’ HURTS! Plus, it makes oral sex really difficult. 
I have to agree with the person who mentioned guys thinking that “lasting a long time” is ideal. Guys, it gets sore. Really. 45+ minutes is not something to brag about. Sure, there is “over too quick” but once you’ve gotten to a satisfactory length of time, anything beyond that is getting uncomfortable and likely making her wonder what’s wrong with her that she isn’t able to make you cum.
I bet you don’t have the bruised cervix issue, though.
For me, I think girth is also a problem because if it’s too long, getting it in to begin with hurts. Whereas if it’s too long, then it’s just not going to go in all the way. Then again, I haven’t been with any frighteningly huge guys (six or six and a half is about the average length of most of the guys I’ve had). The idea of a ten inch dick slamming into me is disconcerting. (And about to make me curl up and CRY!)
I can attest to this from the other side. For about a year and a half after my back injury, I had serious problems reaching orgasm. My (now ex-)wife would get irritated - in both senses of the word - by about the 45 minute mark. Then I’d be frustrated, because I just couldn’t get there. Happily, this is no longer a problem. Unhappily, I’m alone and single. Frustrating how my longest period of available sex also coincided with my period of physical difficulty.
Anecdote;
A former work partner of mine kept bragging about his girth. One day he held up two coke cans together to indicate his size. I gave him :dubious: , whereupon he sheepishly put one of the cans down. I still couldn’t imagine his wife taking too much pleasure in that kind of circumference. It would certainly be well beyond oral.
I had a friend whose husband is 6’10". When they originally hooked up, all her friends bugged her, wanting to know if he was “proportionate,” and they wanted numbers. Her answer?
“I don’t know. Every time I bring a ruler to bed, he takes it away and spanks me with it.”
And that is as far as I think the numbers game should ever go.
During foreplay - when it’s fully erect. It’s fun to measure it, seriously! 
I have a female friend that had a boyfriend she used to call Bud. The reason was she swore to me his unit was the same size as a 12oz Budweiser can. She claims to she did a comparison once.
ETA: RealityChuck So I am guessing your lady friends don’t have a tattoo on on their inner that that reads:
!<- You must be this tall to ride this ride ->!
Ewww!!! I can’t even imagine trying to stuff something the size of a beer can up in there!!? I’m only 5’2" and body parts are proportional, people!!
I recommend some Irvine Welsh. The Cruel Bastard and the Selfish Fucker Get it on.
Yup. And the times a penis size thread pops up (pun intended?), the posts read like metes-and-bounds land surveys.
The difference with the cup size is that you pretty much see what you get with women. There’s not much reason for us to lie about it; it’s readily apparent. The Dopers I’ve met who mentioned it don’t seem to be lying.
I’ve got big boobs. It’s the only body part I’ve got that’s big that is acceptable to be big. If you asked me to measure me arse, I’d not be so willing to admit that it’s huge, too!
In any case, bigger isn’t always better.
My first boyfriend was too small. However, I stayed with him for five years and obviously, his size wasn’t a factor in my leaving him.
My second boyfriend was too big. :eek: However, I stayed with him for two years and his size was also not a factor.
My third boyfriend was juuuuust right! And I married him. We’ve been married for four years. Maybe it does matter this time? Nahh. 
My dicks so small the NHS is treating me for a severe case of ingrowing penis.
This thread is making me a lot better about myself. So how you ladies doing?
Bumping cervix ain’t no fun for me either…