Is it possible to re-potty train my boyfriend?

My boyfriend was raised on a farm with only men. I love him to death but he is so unsanitary. He will go pee the garden or on the side of the house and it really ticks me off. Not only that but when he goes to pee in the bathroom he hardly ever lifts the seat then he gets it all over!! He cleans it after i ask him to but id really rather he stop all together because its really gross. Ive told him numerous times to stop. He gets embarred about it so i think he's going to stop but he doesnt. What can i do?