They usually start laughing, until they see the dead serious look on my face. (siliconhillslawyer.com)
1) Teach students how to instinctively say «Hmmm» and have a very serious look on their face any time a professor says something profound. (redeeminggod.com)
With a totally serious look on his face, Joe stated, «Heck yah, Coach.» (sportstarsmag.com)