Penetration. You want details? Don't ban me because of vulgarity because you asked.
You can edit it out if u want.
A guy has an STD, his sperm carries this STD. When the fluid gets inside the body (can go through cuts, or other holes) it goes to the bloodstream, and then the next person has it.
Thats why homosexual males get it the most, the anal cavity isn't meant for sex and tears.
I have no clue how a lesbian would transmit an STD unless they did it on purpose because there is no insertion.
Your an admin right? Can you get more people to respond or something, it is a lot more fun when more than one person is responding to your comments.