Ohhh you're so close to my ass now slave, huh? So go ahead and get your cock close... no not to my ass, eeewww! Close to the edge! Do it 4 times.
Now you've got some work to do I'm afraid. While you keep stroking you're going to spit in a glass over and over again. Lets get technical, pay attention shit-for-brains: if your glass has a diameter of about 5cm at its base, fill it to a depth of 3cm. If your glass is different, draw a cirlce on paper with about a 5cm diameter and then you can roughly see what volume of gob I'm talking about. If you can't make much spit be inventive - eat or drink something sour to get you salivating, but I expect you're drooling over me plenty already little doggy.
This might take a while... while you're stroking and spitting (oh my god you look stupid) lets talk about something interesting: my ass.
You're totally controlled by it aren't you? It's just turned your little brain to mush. Because you're intoxicated by a beauiful woman's ass, you're sitting naked, spitting over and over into a glass and yanking your little dicky. Wouldn't you love to just slide that G-string to one side and slowly plunge into me? To feel the head of your dick slowly part my beautiful pussy lips: so warm, so inviting, and then feel me wrap around your shaft like a tight glove?
After each spit just focus on wanking for 20 seconds. While you're tugging make heavy breath sounds in-time with your tugs. Make them as deep- and heavy- and pathetic-sounding as possible. Spit and repeat...
Stick the fruit of your labours in that portable freezer over there for now.