Fun is mandatory. So decrees the ‘funniest man with an accordion,’ Weird Al Yankovic, famous for such song parodies as Eat It, Like a Surgeon, Fat, Smells Like Nirvana, Amish Paradise and The Saga Begins. The ‘Mandatory Fun’ World Tour hits Grand Rapids at DeVos Performance Hall, 303 Monroe Ave. NW, on Friday, August 26 at 7:30 pm. Tickets are on sale at the DeVos Place and Van Andel Arena box offices all Ticketmaster ticket centers and by phone at 1.800.745.3000. Prices are $37.50, $49.50, $55 and $85.