This is a vital skill to have in the world of smoking mary jane. You can't very well buy weed on a credit card, now can you? And you don't always have cash on hand. That's life. However, you can always shine your puppy dog eyes and guilt your dealer into
FRONTING you a sack. The amount is whatever you think you can honestly repay, obviously. You're not trying to cheat the man. Because as long as you're in good standing you will always have someone to call, otherwise your calls may not be welcome.
But I digress. The way to get fronted is to first be sure the person has weed. Once you know that you move to phase 2:
asking. Asking is the most important moment when everything you say makes a world of difference to "your guy". Be sure he is in a positive mood before you ask and help that mood along if you have to. Offer him beer, cigarettes, companionship, whatever it takes. THEN you carefully drop the bomb.
"Do you think you can front me?". An explosion goes off in his mind when you say this to him. You think that stuff grows on trees? (Oh wait). Anyway. He paid good money for it!!
Lastly comes the assurance. This is step 3. The last step where you lay it on thick. Tell him you're sorry. Tell him it's a little embarassing. But do tell him you *promise* to pay him back.

And you WILL pay him back!!!