1. glombed on.
When a person inserts himself into a group activity when he hasn't been officially invited.
2. glombed on. To get a ride from someone who is going to an event after finding out that another person is driving there and other people you know are going in their car.
He glombed on to the group of kids going to see the movie.
She glombed on a ride from Robert when she found out he was driving Alicia and Will to the Radiohead concert.