In the United States April 1 is a day when you need to be a little careful . It is April Fool's Day so someone might play a practical joke on you -- a harmless trick for fun . We did a program on fool expressions a couple of years ago . We explained how to use foolhardy and foolproof . We talked about the idiom “A fool and his money are soon parted .” But we left out some things . So , here we are again talking about fools ! Probably the most common definition of “fool ” is someone who is silly and , well , foolish . It is very easy to trick a fool . “To fool ” can also mean to pretend . For example , “The child said he was sick but he was only fooling . He was in perfect health .” If you say , “I was only fooling ” that means you are not serious . You are kidding . So , if you say something to someone as a joke but they take you seriously , you can say to them , “I was only fooling .” Here , you could also say , “I was only kidding .” We often pair “fool ” with the verbs “play ” and “act ” to form the expressions play the fool and act the fool . They both describe someone who is easily tricked or deceived . Or sometimes , we play the fool because we fall deeply in love and cannot think clearly . Sometimes we use it to describe someone who is not easy to fool . For example , if your friend John is really smart and not easily tricked , you could say that he's not one to play the fool . If that is too wordy , you can simply say he is no fool . If you make a fool of yourself , you do something that makes you look foolish or silly . For example , imagine you are at a party . Suddenly your best friend sees a young woman who he really likes . He wants to get her attention . So , he starts dancing . But , no one else is dancing . In fact , there is no music playing . You calmly go up to him and say , “You might want to stop . You are making a fool of yourself .” But making a fool of yourself is better than making a fool of someone else . That is just mean . If a person tries to make a fool of you by yelling at you in public , just walk away . He will end up making a fool of himself . Now , if you are fooling yourself you are unwilling to accept the facts of a situation . In other words , you are in denial . If you think that you can learn perfect English in a very short time without studying or practicing , you are really fooling yourself . Now , when we pair the word “fool ” with “around ,” we get an expression that has several meanings . One is to spend time without any purpose . If you have the day off from work , you might decide to fool around all day . Another meaning is to behave playfully . The two friends were fooling around near the train tracks when they heard a call for help ! But be careful . “Fool around ” also means light-hearted sexual activity . For example , the husband and wife were fooling around in the kitchen when their friends and family walked in for dinner . In these three example , you could also say mess around . It has the same meaning and we use it in the same situations . Finally , we often use the word “fool ” in warnings to others . For example , “Don't fool around with that ! You will break it .” Or , “Stop fooling around .” And the ever popular , “This is no time to fool around .” And that's end of this program . I'm just fooling . We'll back next week with a new show .