at first at a younger age, i thought you only had to grind your genitals on eachother...humping.
i saw my younger brothers (who was a baby at the time) penis when my mom was giving him a bath. up till probably 7th grade, i thought a guys penis stayed that length/size (size of a pinky). so you can imagine what a shock porn gave me.
when i found out you have to put the penis into the vagina, i thought you only slide it in once. like it actually took a few minutes to slide it in, and once you did, sex was over. didnt know you have to pump it. lmao.
Edit: oh yes, and i had no idea about orgasming. i used to get random aims from people wanting to cyber. when they asked me if i want to orgasm, i would just brush over the question like i didnt see it. it would get them real frusturated. now i know why.