Door Alert

It might as well be midwinter. 10C and wet so I've stayed inside most of the day. Mr isbi visited The Office for the first time in ages and I gather it wasn't a totally unprofitable afternoon.
We did venture up the street to the café for lunch. I was intrigued by this on the door, presumably to alert staff when it opens.
There will be no sneaking out without paying.
I thought it just about qualifies for a Silly Saturday tag.