However, not all these conversations are successful, since one person can easily misunderstand what the other is saying. Also, one or more members of the group can be kept out of the conversation, for example, Ted doesn't understand them when Marshall, Lily and Robin talk telepathically about how to talk Ted into dyeing his hair blonde, and Lily doesn't "hear" him, when Marshall stops the others telepathically from telling Lily that the Pretzel Vendor is not Barney's doppelganger. (Doppelgangers)