I know an easy way to beg. It works well with my mom but sometimes it doesn't. Luck does have to do with it though. I have it step-by-step.
First, you look the person strait in the eye. You do this for the whole time you are begging.
Next, you widen your eyes but not too big; it might gross the person out.
Then, you have to think that you want it and think "please" and make sure you tell it in the eyes. Body language is real important!
Finally, you do this until the person says yes or no.