If you use the person's butthole like a telescope and they let one rip, you might get poo particles in your eye but they gas cannot infect you.

"Farting on a pillow can cause pink eye.. . This is a popular myth amongst school-age pranksters that asserts a person who uses a pillowcase that a practical joker farted on will later contract pink eye. You cannot get pink eye from a fart. Flatulence is primarily methane gas and does not contain bacteria. Additionally, bacteria die quickly outside the body."