I love it because it seems to be an ultimate act of intimacy and eroticism, and also love. I enjoy the sensation of a friend's penis in my mouth, and love the apparent joy and pleasure it gives him to ejaculate as a result of my mouth and handwork. I absolutely love the feeling of his sperm shooting or spilling into my mouth, and feeling it's smooth viscosity as I swirl it around. And the look on his face when he looks at me and sees me swallowing it - a priceless gift both of us enjoy.
Last but not least - I love being in public with my friend whom I've sucked off and whose cum I've devoured - secretly watching him and remembering all the sensations I felt during our oral adventure. For example, walking with him into his parents' house for a visit (dinner, etc) moments after I feasted on his semen in the car in a "last minute before the visit blowjob".
And -- being in public with several guys whom I've feasted on - and with each of them not knowing about the others. I can look around a table or be in a group at a party, and see several guys with whose penises I am well acquainted. Just the thought of that is incredible....
Better ye