bend over backwards

Also, lean over backwards. Exert oneself to the fullest extent, as in Dad bent over backwards so as not to embarrass Stasia's new boyfriend. This phrase transfers the gymnastic feat of a backbend to taking a great deal of trouble for someone or something. [c. 1920] Also see under fall all over.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.