To sign "Johnny", you will fingerspell the letters J-O-H-N-N-Y. Keep your dominant hand steady at about shoulder height, with your palm facing mostly outward. Smoothly transition through each letter, and for the double 'N', give your hand a slight bounce or slide it slightly outward to indicate the repeated letter.
Sign 'MY FRIEND NAME' followed by fingerspelling J-O-H-N-N-Y.
Fingerspell J-O-H-N-N-Y, then sign 'COME PARTY', making sure to raise your eyebrows at the end to indicate a yes/no question.
Sign 'YESTERDAY I SEE' and then fingerspell J-O-H-N-N-Y.
Sign 'MY FRIEND NAME' followed by fingerspelling J-O-H-N-N-Y.
Fingerspell J-O-H-N-N-Y, then sign 'COME PARTY', making sure to raise your eyebrows at the end to indicate a yes/no question.
Sign 'YESTERDAY I SEE' and then fingerspell J-O-H-N-N-Y.
Yes, unless the specific Johnny you are talking about has been given a unique "name sign" by the Deaf community. Otherwise, fingerspelling is the standard and correct way to refer to him.
For double letters, you can either give the 'N' handshape a small, quick bounce, or slide it slightly outward (away from your body) to show that the letter is repeated.
No, try to keep your eyes on the person you are signing with. It takes practice, but looking at your own hand can break eye contact, which is a very important part of ASL grammar and etiquette.
