1p or P 
/ˈpi:/ noun
plural p's or ps or P's or Ps /ˈpi:z/ /ˈpi:/ noun : the 16th letter of the English alphabet [count] ▪ a word that starts with a p [noncount] ▪ a word that starts with p
mind your p's and q's also US watch your p's and q's
: to be careful about behaving in a polite or proper way
▪ We knew to mind our p's and q's around our aunt.
▪ We knew to mind our p's and q's around our aunt.
