of all things
From all the possibilities, as in I said I'd help in any way I can, and of all things they want me to handle publicity. This term, generally expressing surprise, was first recorded in 1925.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.