{n. phr.} State of feeling beaten, ashamed, or very obedient, as after a scolding or a whipping. * /The army sent the enemy home with their tails between their legs./ * /The boys on the team had boasted they would win the tournament, but they went home with their tails between their legs./ (So called because a beaten dog usually puts his tail down between his legs and slinks away.)
TAIL BETWEEN ONE'S LEGS
Meaning of TAIL BETWEEN ONE'S LEGS in English
Dictionary of English idioms . Словарь английских идиом. 2012