It appears that the COVID-19 QR code generator government web site does not allow emojis, but it does allow hieroglyphs, so it seems I have managed to have the UK government digitally sign a penis.
The QR code, signed by the government/NHS, includes
I know it is childish, sorry, and you definitely should not check in to 10 Downing Street by using this barcode, obviously. That would be bad. It does show how daft it is making these QR codes so huge by digitally signing them though. See the other blog post for more details on these QR codes, and what else is wrong with them.
There is a practical use though - making a QR code for your own home will allow you to "check out" of where you have been, otherwise the app assumes you were there until Midnight.