DS (4) loves pretending to be someone else. He wanted to be me recently and I was him. He had a lot of fun being the "adult" and I had even more fun throwing tantrums and not listening
. Interestingly for the last few weeks anyway his behaviour on the whole has been a lot better!
Tiredness and hunger are definite triggers for DS. I have been teaching him some deep breathing recently (not in the middle of a tantrum) which when he does will short circuit a tantrum enough to be able to validate his feelings, which helps, even if he is still not getting his way.
