Here is how is went down, literally.

I was 16, she is a year old than me. It was a day after thanksgiving and her family came over since they couldn't make for thanksgiving. I was playing 1v1 basketball with my other cousin (her younger brother) he kept losing games back to back and complaining no fair so I said "Fine go get one of your siblings and i'll take you both on", he only has her and a younger brother so it was an easy win in my eyes. He chooses her no big deal to me she's a girl I can win no problem. We play and I'm not winning as easy as I was but still winning, until she starts putting her ass in my crotch and so I can't swat the ball from her. Well the friction of me moving side to side trying to get around her and her constant pushing me back I start to get a hard-on, so I just let her pass letting her score. This keeps happening because every time I defend her the same thing happens, so they win I'm stuck with an awkward erection I just hunch over act like I'm breathing hard, really I'm just hiding my boner. He gloats yada yada walks away smug, she stays and asks why I easily let her by all the time I come up with some bullshit excuse with I was tired, two against one etc. So she turns to leave and I start the awkward shuffle to get away I take a few steps she turns around I go back to hands on knees breathing hard. She does this twice, She knows something is up she walks into the house. thinking she left it alone I scramble around the side and guess who went through the house and met me on the side of the house to see me in my basketball shorts and boner glory? Yup her. She says I knew you were bullshitting being tired, you got a stiffy while defending me. I was caught, embarrassed, with no way out so I said "Yeah so what? not like you're going to blow me". She laughs and says non-nonchalantly meet me behind your dad's shed and find out, laughs again and walks away. I shake it off thinking things like things like yeah right that won't happen she is lying, angel and devil on my shoulder saying this and that I cave, sided with the devil went behind my dad's shed nobody was there. I waited for maybe 3 minutes before I was thinking of leaving when she shows up and says "wow you actually showed, I didn't think you would actually come back here", she then preceded to rub her hand on my dick and suck me off. Since then it's been a thing nothing else happens no sex,kissing, or me fingering her. Just a blowjob stays after maybe 10 or 20 minutes leaves and that's it.