VIDEO: College students pull fantastic April Fool's prank on professor

Simple. Brilliant. Hilarious.

We're a bit jaded by the annual deluge of April Fools' pranks - corporate brands trying to be funny, we are looking sternly at you - but this simple trick from students at a US college had us in stitches.

The unnamed professor at Aquinas College in Grand Rapids, Michigan, has one classroom rule - if your mobile rings, you have to answer it on speakerphone.