Where are my napkins?

So, rather pathetically, I collect Pret a Manger napkins here at my desk, as a useful resource for mopping up spilled water (better than tissues!) or dealing with short-term food/moustache management issues.

I come in this morning, and my napkins are gone! Where are they? Why have they been taken? What unspoken rule have I broken by accumulating napkins? We may never know!