I'm travelling abroad Russia. It happens that I see things which I haven't seen before (obviously), and it isn't necessary about culture (not so straightforward). For instance, recently I saw a payphone with internet access:
I don't know if it's a casual thing in some countries, but I haven't seen not only things like this in my life, but also any working payphone for last ~18 years.
So I wondered if it's possible to submit a problem on codeforces using it. Surprisingly, the payphone was quite convenient, one just needs to get used to it :)
So I challenge everyone to get AC on any problem from the cf problemset using any non-trivial device like smart tv idk or a fridge or whatever your imagination tells you to use. Good luck and have fun!