Prague - Change of Guard ceremony

It was our first visit to Prague and we were determined to do all the touristy things - Change of Guard of course being one.
During these ceremonies, or even otherwise, I always look for some expressions on the guard's faces, but never get to see anything but a stoic face and focussed eyes.
I was just wondering if they ever get to cough or sneeze while guarding the posts, and just then one of them did! Pity I couldn't capture it!



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