Today we talk about two expressions involving letters of the alphabet . They both warn us to be careful , and they sound similar . But their meanings are very different . Here is the first one : to watch our p's and q's . When we watch our p's and q's , we are on our best behavior . We are careful of our language too – so , no swearing . We do things politely and without causing trouble to others . The expression is something an older person might say to children . “When you go to school , watch your p's and q's and mind your teachers .” There are several stories about how the expression began . Some word experts say it comes from people drinking in taverns or bars , places where alcohol is served . Bartenders would keep track of how much people drank by counting their pints (p's ) and quarts (q's ). Other experts say the expression comes from the classroom . Schoolchildren were taught to be careful writing the letters “p ” and “q ,” which are easy to confuse . And other experts say the phrase may come from the early days of the printing press . Letters were set in presses backwards so they would appear on the printed page correctly . Now on to our second expression : to dot our i's and cross our t's . To dot our i's and cross our t's means to be very careful . But it means to be careful about procedures . We make sure we have followed directions correctly and have done everything the right way . While it may have its roots in spelling correctly , we use this expression in many situations . For example , when the TikTok star read her contract with an advertising company , she was careful to dot her i's and cross her t's . She didn't want anything to fall through the cracks . She didn't want to overlook any small detail that may affect her business . If you are making a deal or spoken agreement with someone , a friend might warn you to dot your i's and cross your t's . Be careful of the small details . It is common knowledge that the smallest details are often where mistakes are made . So , that is why it is important to dot your i's and cross your t's . Now , let's hear two friends use these expressions Are you sure you packed everything ? Yes , I'm sure . Please don't ask me again ! Well , you usually forget something . Remember last time … at the airport ? Let's not bring up THAT again . I won't forget my passport this time . I just wanted to make sure that we dot all our i's and cross all our t's . By being careful and thorough , we save time and money . Don't you ever get tired of being careful and thorough ? Don't you just want to be crazy and impulsive … for once in your life ? Come on , throw away that list ! What are you doing ? Give me my list back and behave ! Seems like you not only have to dot your i's and cross your t's … you also need to watch your p's and q's !