老若男女
rou.nyaku.nan.nyo
Literally: old – young – man – woman
Alternately: All people. Absolutely everybody, regardless of age or sex.
Notes: While it is not entirely wrong to read this phrase with the more standard character pronunciations rou.jaku.dan.jo, the all-Ns version above is generally considered more correct.

Searching for this phrase gives you SO MANY stock images of generic collections of people.