OK, about to post my sketch, and I've just noticed it's Science Faction, not Science Fiction. Whatever that means. I'm not writing another, anyway. 
LEADER: [Alien voice - 70s Dr Who, all slow, raspy and malevolent] Is all in place to begin the scheme?
SNARGLE: [Same voice] Yes, my lord.
LEADER: How long until the detonation device is ready to function?
SNARGLE: 25 Earth minutes.
LEADER: [Quietly] Minutes. [Standard] And then how long until those ignorant worms the humans are entirely annihilated?
SNARGLE: [Relish] A mere 17 Earth minutes, sir.
LEADER: Minutes, Snargle.
SNARGLE: Pardon me, sir?
LEADER: [Speed up speech to normal rate from here] Minutes, not "Earth minutes". Just minutes. There's no need to specify Earth minutes. We're on Earth. Only the Earth has minutes.
SNARGLE: Oh! I see. You mean we don't need to say "Earth minutes" because our race don't use them?
LEADERR: Correct.
SNARGLE: We don't have minutes on our home planet of Pnang.
LEADER: Just Pnang! I know it's our home planet! I'm not likely to forget that, am I? I know where minutes come from and I know where I live! Just leave out the adjectival irrelevance, alright? It's not really military.
SNARGLE: Sorry, my lord. Shall I tell you about the explosion?
LEADER: Oh, yes! Tell me the vast radius of the blast that shall destroy the ignorant Earthling worms!
SNARGLE: 380 Earth miles! [Beat] Miles, I meant just normal miles! [Beat] Not normal, stupid; stupid abnormal Earth miles - but there's no need to specify the Earth bit. That's taken as read.
LEADER: For Plaark's sake, Snargle! Why do you even have to use miles at all? What's wrong with good old fashioned Pnang Feltrometers? It's really confusing doing the calculations in my head when you say miles. Why must you insist on using this filthy Earthling terminology?
SNARGHLE: Well, you're the one who started speaking English.
LEADER: I know! But I thought we could all learn English as a way into the mindset of our human enemies.
SNARGLE: You said they were ignorant worms. Not much to be learnt by thinking like ignorant worms, is there? Erm, sir.
LEADER: Shut up! Just use feltrometers from now on. [Pause] Actually, no, you can carry on using miles...they're probably actually better. It is quite useful to have a unit of measurement that is standardised, isn't it?
SNARGLE: Unlike ours, which is variable, because it's based on the length of the grand vizier's flurglewhacker, which can vary with altitude and mood? Yes, I always thought so. So, we'll keep miles.
LEADER: Yes. And, pounds. Money. That decimalisation thing is much, much easier than anything to do with square roots.
SNARGLE: And names, Sir?
LEADER: Oh, yes! I forgot that one. It really is handy to give everyone a different name, much less confusing than when everyone's called Snargle, Snargle.
SNARGLE: Yes, Lord Snargle. And shall we keep the numbers too?
LEADER: Oh, yes, we might as well. To be honest, when all the numbers are called Stwag, it's a bit of a mess. And it actually makes the feltrometer calculation all but impossible, even if the grand vizier's flurglewhacker is right in front of your face. But, still, that's it, everything else on Earth is valueless and we must destroy the miserable human worms!
SNARGLE: Right you are, sir.
LEADER: Aaargh! Thwunk me, Snargle, what in the name of Crudge is that on the scanner-o-visor-screen-o-scope?
SNARGLE: That? That's a human, sir. One of the paltry human worms!
LEADER: Oh. Ah. They, erm, they look quite tough actually. And pretty smart too. Perhaps we won't try to, err, attack them with an army of just 6, after all.
SNARGLE: Oh. Fair enough. What did you think they looked like, sir?
LEADER: Little, sort of squishy long stretched out fellers. Sticky. No thumbs or suchlike. Crawl about the mud.
SNARGE: I think you're thinking of worms.
LEADER: Oh! Do you know, Snargle, I think I can see how that problem arose.
SNARGLE: [Under breath] Stupid flurglewhacker.
