tickle the dragon's tail

verb3

1. •
   To do something that has a risk of going catastrophically wrong.

   • Climbing so close to an erupting volcano was tickling the dragon's tail.
2. •
   To bring two subcritical masses close together in order to find the edge of criticality.

   • The laboratory head tickles the dragon's tail whenever we have guests as a show of machismo.
3. •
   To annoy an irritable person.

   • Don't tell him the headline's misprinted; you don't want to tickle the dragon's tail.