O.P.P.

MIL: Here's a link, but the highlights:

O is for Other, P is for People scratchin' temple
The last P...well...that's not that simple
It's sorta like another way to call a cat a kitten 

As for the ladies, OPP means something gifted 

The first two letters are the same the last is something different 

Its the longest, loveliest, lean -- I call it the leanest 

It's another five letter word rhymin' with cleanest and meanest