Lights up on MOUSE 1 and MOUSE 2 slouched on a couch watching TV.  MOUSE 3 walks in and joins them on the couch.  The only marker showing that they are mice is a pair of ears on each of them.  Maybe tails if we're feeling fancy.

M1: Hey mate, how was work?
M3: Yeah, it was okay, some good, some bad.
M2: How so?
M3: Well, they might have put a cure for cancer in me.
M1: Not bad.
M3: But I'm pretty sure they gave me cancer before that.
M1: Ooh, harsh.
M3: The lab was pretty quiet today, so I was mostly just sitting around, it gave me time to think.  Then I fell into that existentialist hole and started wondering where my life is actually going...
M2: Psh, at least you don't have a massive ear on your back.

M2 twists around to reveal ear.

M2: Real hinderance with the ladies.
M1: From what I hear, your mum didn't care.
M3: It's funny, you'd think that a mouse with an ear that size would actually be able to listen.  I mean, five years down the track, when I'm an old mouse, what will I be telling the great great great great great great great great great great great grandkids?
M2: You'll probably be telling them that you're impotent so they don't actually exist.

M3 looks crushed, M1 arches an eyebrow.

M1: At least they won't be inbred.
M2: Hey!  Hey!  That was one time, okay?  One time!  We all look alike!
M1: Racist!
M2: Ugh, you know what?  Fine, whatever.  If anyone needs me I'll be in the wheel.

M2 walks out.

M3: Who pissed on his cheese? (Beat.  Then frowning slightly:)  Oh yeah, that was me.  Anyway, how was your day?
M1: Pretty good, oh and there's this awesome musician playing at the pub tomorrow night, you up for it?
M3: Yeah okay, what's his name?
M1: The Pied Piper.

Hard lights down.