Will Ferrell was doing some press for "Anchorman : The Legend Continues" when a reporter's phone rang. It said "Mom" so, he decided to answer it. Thus proves, once again, why Will Ferrell is the BEST.

From the reporter's Youtube page :

"Something funny happened at the beginning of the interview. I used my phone to record audio for the interview for the first time. I thought this would prevent my phone from ringing, but this apparently is not the case. My mom called and Will picked up. Hilarity ensued. Note to self, put your phone on airplane mode if you want to record audio.