What exactly is a wedding telegram? Is it like a singing telegram where you have someone dressed funny who goes and delivers a message to someone? If it is, I would suggest to stay away from those unless it is actually you in the suit proposing marriage to someone.
If it is an invitation, you can do some funky color/design on them and have the wording inside show your personality. Like if you are an upbeat/retro couple you can sy something like:
The Hip-Cat and Hip-Goddess strongly agree that they want you to join them as they join hands and celebrate this funky thing called love and groove the night away to funky tunes and fantastic food!
(ok so thats a bit out there- but fun nonetheless- and you can even incorporate your party theme around it)