I put this on my phone a few weeks ago:
Possibly because I live in the US, no one has gotten it so far. I did have one person who mistook it for "Intel inside" and asked me what type of phone it was, though.
I'm thinking about adding an Aperture Science logo, but around here, that would just be following the trend.
And yes, that is clear duct tape. The otterbox isn't dustproof, so I DIY'd it.
If you don't get the reference, you really need to try a Pratchett book. I suggest Men At Arms.