I did this with my third grade elementary students after teaching the phrases in Let's Try 1 Unit 2. I made this up right before class, so I didn't prep any materials to go with it, but the students had so much fun.
First, I wrote the greetings on the board:
1. Handshake
2. High 5
3. Fist Bump
4. "Dap me up" (I explained that this has a strong sense of comraderie - I did the variation where you slap their forearm and then slide the hand down and grip their fingers - how do I explain it lol)
5. Nod (Paired with saying "Hey" or "Wassup/Sup/What's Up" - A quick flick of the head upwards)
These are the ones I thought of on the spot, but definitely add more.
Then, I demonstrated them with my JTE.
After we went through them a couple times, I had students pair up and they had to do the greeting when I called it out.
Afterwards, I had the pairs create their own greeting/handshake. Then, I had each pair show their handshake to the class.
They had a lot of fun with it, so they asked to create another greeting, and we had enough time, so they got to do it again.