A pronunciation \mis-ˈchē-vē-əs\ and a consequent spelling mischievious are of long standing: evidence for the spelling goes back to the 16th century. Our pronunciation files contain modern attestations ranging from dialect speakers to Herbert Hoover. But both the pronunciation and the spelling are still considered nonstandard.
Examples of MISCHIEVOUS
<the children had been so mischievous that we had to pay the babysitter extra and then clean up the mess>
<punished for their mischievous tricks on the neighbors>
In passing the test of killing itself if infected, cancerous or genetically mischievous, a cell by definition dies. —Matt Ridley, Genome, 1999
… Pedro Martinez, could be found in the dugout, usually wearing sneakers instead of spikes, his tongue flying about as fiercely as one of his mischievous fastballs. —Tom Verducci, Sports Illustrated, 11 Oct. 1999
Setsu grew, too, from a mischievous, laughing little girl into a gay, willful, pretty girl. —Pearl S. Buck, The Big Wave, 1947