John Oliver showed off his very own salmon canon, which is a real thing. It's actually used to help salmon pass through hydroelectric dams when they swim upstream. Oliver's version on the other hand, was used to launch salmon at his peers.

Check it out:

He launched it Jon Stewart.

Jimmy Fallon.

Michelle Beadle.

Dwight Howard.

Kelly Ripa.

Jesse Tyler Ferguson and Eric Stonestreet.

Stephen Colbert.

J.J. Abrams.

R2-D2.

David Letterman.

There's more! Watch the video!