Flippant

Flippant- Acting flippantly is being  rude, irrelevant, or joking when one should be serious.  Mostly, being flippant is not taking a grave or important event seriously. It could be making rude or inappropriate remarks or it could be it could be dancing around in a graveyard on people’s tombstones. 
# When Dylann Roof was put on trial for the shooting in Charleston, he chuckled and said “ I had to do it,” giving no respect or even thinking about any of the families affected by him. 
# https://www.youtube.com/watch?v=Vmb1tqYqyII