For me it was by watching Junjou Romantica in Youtube when I was 16. I mistook Misaki with a girl and I thought it was shoujo. So, it was a real shock for me, I didn't even know yaoi existed in general and I was super innocent even at that age. Anyways, at first I felt disgusted (I grew up in a quite homophibic family), but after that shock I became curious and kept watching. Now I only read yaoi lol.
One day when I was sick in middle school I decided to randomly watch an anime which was Junjo romantica. First episode I love and I thought it was cute so I watched the rest. First yaoi manga tho was Ten Count reply
