Stop in for a cup of coffee

It is a bad day, when you are all ready and set up to weld. Using a TIG welder. Everything set up, turn on the gas, no gas.WTF ??? Somebody used my rig to weld with in my absence and did not turn off the tank valve.:mob::mob::mob::mad::mad::mad::wtf::wtf::wtf:
:BangHead: Do you have an idea of who used it?