Any kind (of a thing) in general. You don't need to buy the expensive stuff, any old laundry detergent works just fine.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
No particular, whichever or whatever, as in Any old brand of detergent suits me. [Colloquial; mid-1800s]
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.