Why is easter on april fools day this year? Or is the calender a joke?

Easter isn’t determined by the calendar, but by phases of the moon (astrology). 

A bit of history for you:

In 325, the Council of Nicaea established (among many other Christian precedents) that Easter would be observed on the first Sunday after the full moon on or following the Vernal (or Spring) Equinox.

This year, that full moon falls on Sat, March 31. 

Yes, it's strange that it's on April fools day. It's also early this year.

yeah that is weird.