At an Argentinian press conference this week one player responded to a question by saying "ask Egg".
"Who's Egg?" said a puzzled Australian journalist before Pumas coach, Daniel Hourcade, stepped in to reveal his alias.
The nickname comes from his childhood when his brother Luis decided his head looked like an egg.
"Sometimes people call me by my real name and I do not realise they are talking to me," said Hourcade. "I am the Egg."
Five-eighths Nicolas Sanchez, one of the most senior players in the squad, is known as "Puppy", but only because his older brother was "Dog". Santiago Cordero is known as "Corderito" because of his family name, which means lamb.
He is also called "Fluff".
"I am called this because I have a lot of hair everywhere," Cordero joked.
Juan Martin Fernandez Lobbe is known as "Cork". His mother gave him the name because he was a plump child.
Tomas Lavanini is known as "Tongue" because he does not talk much.
Juan Martin Hernandez has acquired the name "El Mago", or The Magician, because of his skills.
Only Juan Pablo Socino and Marcos Ayerza have more traditional rugby names.
Socino is called "Matmut" or Mammoth, because of his 110kg physique.
Leicester prop Ayerza is "Toro", or Bull, because he is good in the scrum.
Pablo Matera has the sobriquet, "Loco", or Mad, but everyone insists it is meant in a nice way.
- AAP