Photo Thanks Phrase A Question For All The Native Speakers Of English - What's The Meaning Of The Phrase - Getting Tail.?

A question for all the native speakers of English - what's the meaning of the phrase - getting tail.? - photo thanks phrase

The situation is as follows. A man sees a photo of two men in the papers and tells her daughter: "Your friends are the tail." The picture shows two boys and two girls kiss. Can you get a word or phrase to the tail. Thank you.