I have found two ways that help the messiness of Go-gurt tubes.
One way is to freeze the tubes of Go-gurt. An adult will have to open the tube but it becomes a nice frozen snack which will not melt too quickly.
If your child does not like cold or if you just bought them, another way would be to cut the corner off and place a straw inside. This way the hole is smaller and the child will have a harder time making a big mess to clean up.