there are many good moments and scenes between the Doctor and the Master in 'Masterplan', but this is the one that made me laugh the most. they revert back to kids whenever they're together.
[transcript]
DOCTOR: I could say “I told you so” again. In fact, I will. I told you so.
MASTER: Ugh, what's it doing?
EMINENCE: That which cannot be possessed must be destroyed.
MASTER: It's cutting off the air supply!
DOCTOR: More than that – it's pumping the air out. Suffocation... I must admit, it's not exactly how I wanted to die.
MASTER: Oh, you fool. We can use our respiratory bypass systems. I always used to beat you in metabolic control classes.
DOCTOR: All that means is you'll last ten minutes longer than me!
MASTER: Which means I'll get to see you dead.
DOCTOR: (out of breath) Really? Even now that's what matters? (he drops to the floor)
