A man walks into a bar and sees a sign that says, "Free drinks for anyone who can make the bartender laugh." So the man decides to give it a shot.
He goes up to the bartender and says, "Hey, did you hear about the mathematician who's afraid of negative numbers? He'll stop at nothing to avoid them!" The bartender chuckles and pours the man a drink.
Encouraged by his success, the man tries another joke. "Why was the math book sad? Because it had too many problems!" The bartender laughs even harder and gives the man another drink.
Feeling cocky now, the man tells one more joke. "What do you call a fish wearing a crown? King mackerel!" But this time, the bartender just stares at him blankly.
Confused, the man asks, "Did that one not make you laugh?" The bartender replies, "Oh, sorry. I'm just a little fishy about giving free drinks to people who make puns."