The deletion of entries in SQL is dangerously easy, which, if you haven't noticed yet, is a recurring theme. Here's the command syntax:
mysql>DELETE FROM table_name WHERE conditons;
So to delete all chicken jokes from your table, you'd use the following query:
mysql>DELETE FROM Jokes WHERE JokeText LIKE "%chicken%";
One thing to note is that the WHERE clause is actually optional. You should be very careful, however, if you leave it off, as the DELETE command will then apply to all entries in the table. This command will empty the Jokes table in one fell swoop:
mysql>DELETE FROM Jokes;
Scary, huh?