One of my favorite writing exercises is the random word. Several years ago I joined a writers workshop that did Short Story in a Week. Five groups of five random words were given, and participant could use one or all of the lists in a short story exercise.

Random are great ways to generate ideas. Take this generator.
It gave me these words:
cheese
empire
attack
fairy
sky

The fairy empire is in heated battle with the cheese loving citizens of Wisconsin, and taking to the sky, ready to attack!

A silly sentence, but fun, and able to add more ideas.

Search for random word generators on google. If you have a specific genre you like then add that genre. Try it a few times to get the creative juices flowing.