Summarize the following:
While most people who are present at the dinner may know you, not everyone will. A simple greeting and your name will do. An example of introducing yourself as a part of the speech is “Hi everyone, my name’s Morgan.” This could be through being a parent, sibling, or a lifelong friend. Include that you appreciate being asked to speak.  An example of how to start is “I’ve been friends with Sam since preschool, and I am honored to be able to congratulate Sam and Corey tonight.” If you have a funny story about your relationship with the couple, this is a perfect time to share it. For example, "With the amount of heated competition that goes on during our board game nights, I'm surprised that Sam and Corey are even still talking to me, let alone are letting me stand up here tonight!" Show your appreciation for all the people who have gathered to celebrate at the rehearsal dinner. Say something along the lines of “Thank you, everyone, for being here to share and celebrate this wonderful occasion.” Now is also a good time to acknowledge any special people in the audience or who couldn't make the event. For example, some family members may have travelled a long way to be at the rehearsal dinner. Saying "We are so happy that John and Anne have travelled all the way from Canada to be with us on this special occasion," works well. Similarly, if there are any special people that couldn't be at the wedding, as they may be unwell or have recently passed away, acknowledge them at this time too.

Summary:
Say hello and introduce yourself. Explain your relationship to the couple. Thank and welcome everyone at the rehearsal dinner.