Golf
Masters has very strict rules with phones banned and strong punishments in place

Masters spectators face severe punishments for carrying a mobile phone around the course at Augusta National Golf Club. Phones and other electronic devices are one of many items strictly prohibited during the tournament.
Augusta’s website features a lengthy ‘dos and don’ts’ page which tells those planning to attend the Masters what they can do. Some of the rules are obvious – such as not carrying weapons – but others are a little more niche. Those attending for the first time may be unaware that mobile phones are prohibited around the 18 holes and can be handed over at free check stands.