Riddle #3

Hey guys, sorry for the long wait this time. My teachers decided to give us loads of homework this week, and with my other extracurricular activities, I've been staying up to one each day. Well, you guys have been waiting for it, so here it is:

During an incredibly elaborate hazing stunt during Stanford pledge week, Trey sheik suddenly found himself alone in the Sahara Desert. His desire to become a fraternity brother was now overshadowed by his desire to find something to drink. As he wandered aimlessly through the desert sands, he began to regret his involvement in the whole frat scene. Both hours and miles had passed and trey was near dehydration. Suddenly he came upon an oasis.

There, sitting in a shaded kiosk beside a small pool of mango nectar, was an old man named Al Donte. Big Al not only ran the mango bar but was also a travel agent and could book Trey on a two humped camel back to Stanford. At the moment, however, Trey desired nothing but a large drink of that beautifully translucent and refreshing mangoade. AL informed Trey that he sold the juice only in eight ounce servings, and the cost for one serving was $3.50. Trey frantically searched his pockets, and though he found much sand, he also discovered that he had exactly $3.50.

Trey's jubilation at the thought of liquid coating his parched throat was quickly shattered when Al casually announced that he did not have an 8 ounce glass; all he had was a 6 ounce glass and a 10 ounce glass, neither of which had any markings on it, Al, being a man of his word, would not hear of selling any more or any less that an 8 ounce serving of his libation. Trey, in desperation, wondered whether it was possible to use only the unmarked 6 and 10 ounce glasses to produce exactly 8 ounces in the 10 ounce glass. Do you think it is possible? If so, explain how, and if not, explain why.

By the way, do you have a facebook, twitter, tumblr, or gmail? If you do, could you please reply? Thanks! My next riddle will be coming up in a few days instead of a week. I'm making it up to you guys since you guys had to wait so long.