(Portland, OR)  --  Multnomah County Sheriff's Deputies will be serving up burgers and fries Saturday for a cause.  The deputies are participating in Red Robin's 12th Annual Tip-A-Cop fundraiser to support Special Olympics programs.  The event takes place from 11 a.m. to 2 p.m. and again from 5 p.m. to 9 p.m. at all Oregon Red Robin locations.