Huffpost.com says there are seven things you shouldn't touch on an airplane.

Armrests tops the list of things to avoid.

Also on the list of things you should avoid touching: tray tables.  A 2007 study revealed four in six tested positive for MRSA bacteria and noroviruses.

Rounding out the list of things you shouldn't touch on a plane: The inside door handle of the restroom, the restroom faucet handles, the toilet flushing button, blankets and the toilet seat.