A metric tonne (1000 kg) should be called a megagram (1 Mg).

I'm an engineer, and I make it a point to teach young engineers that "a ton" can mean any one of three things:

• Short ton = 2000 lb
• Long ton = 2240 lb
• Metric ton = 1000 kg = ~2204 lb

And which is being used is often not spelled out, but is just known from context, and usually should be clarified. I once nearly got in trouble by thinking a measurement was in short tons when it was actually metric tons.

So my own act of rebellion is to use "Mg" when I'm writing my personal notes.