If all you need is a simple search, just type it in and hit enter. If you are looking for something a little more complicated, here are some hints for common kinds of searches.

dog

Any jokes with the word dog.

title:dog

Only jokes where the word dog is in the title.

text:dog

Only jokes where the word dog is in the text of the joke.

text:dog -title:dog

Only jokes where the word dog appears in the text of the joke but does not appear in the title of the joke.

"light bulb" OR lightbulb

Find jokes containing either of the two common spellings of lightbulb.