what is the bruise/scar thing on the underside of a penis? Does it have a name? Why is it there?
Until one of the human med folks wanders by, can you post a broken link to a pic? I have no idea what you are referring to.
i don’t want to search the internet for pics of penises, so no i cant post a pic
Absent a picture, I can’t offer any insight. I’m not really familiar with the bruise/scar you describe.
Have you consulted a doctor?
You mean the frenum - the stretch flap also on the underside of your tongue?
Or do you mean the circumcison scar found in different forms on different guys’ junk?
Frenulum.
To clarify, is this a circumcised or uncircumcised penis you’re asking about? And how large is your sample size? I just checked mine (again), and I don’t see anything which could remotely be described as a bruise or a scar. You or the owner of the penis in question might want to consult a doctor about this.
Peter Marx.
Joke of the day. 
It could be a circumcision scar too.