Penicillin Shot?

I have strept throat at least that's what my doctor's nurse told my from the symtoms i told her I was having,so she made me an appointment for this afternoon when I asked her how strept throat is cured, she told me the doctor normally orders a penicillin injection and she said it goes into your butt.
Now I am worried,about it and am thinking about cancelling the appointment.
I did some research here in the questions,and found some people take the shots in the butt laying on the exam table and others take the shot standing up.
Which is the best way,laying on the exam table ar standing up,and how bad do penicillin shots hurt?
One other thing that really bothers me,will I have to remove by briefs for the shot? That would embarass me so much.

I had one last year when I had strep throat and I was expecting it to painful but being the brave little soldier I am, I laid on the bed and held the corner of my undies and trousers down with a hand and the nurse told me to wiggle my toes, apparently this helps, and then she threw the needle into my butt which was a quick sting and then as the medicine went in it was just a dull ache which lasted about 10 seconds. The doctor kept me distracted by asking me something and before I knew it the nurse was telling me I could sit up. It certaintly didn't hurt and my throat was much better the next day.

I may be 20 but every doctor and surgeon I know say I am brave little soldier, I just like to get things over and done with it gives me less time to worry and get worked up about it.

No, it won't hurt much, it is really a quick thing, hardly noticeable. Your briefs will be on, just the corner, probably, held down for the quick shot. The shot is necessary.......or, you may be given pills for this. Do whatever the Dr. says to do, don't miss that appointment! Strep is nothing to fool around with...........you'll be fine.

Lying down will be better, as the injection, benzathine penicillin is painful. It goes into the upper outer part of the butt, so the briefs will have to be pulled down a little on one side. It is better to take the shot. Otherwise, you will have to take oral penicillin for 10 days.