These are a couple videos of model maker Maladroit Modeller showing off his recent build of the twelfth Doctor's TARDIS, complete with bigger on the inside (dimensionally transcendent) interior thanks to a clever mirror-based optical illusion. It's actually the same sort of illusion that makes those 'disappearing coin banks' work if you know what I'm talking about. You know what really is bigger on the inside though? "Please don't say your butt." I'm a smuggler's dream, I'm just saying. "What?" I can fit anything up to a shoebox.
Keep going for two videos, the second of which reveals how the illusion works.
Thanks to hairless, who wishes bathroom stalls were all bigger on the inside.