The 7th Inning stretch is a cheery tradition at games: be prepared to know the lyrics, to stand up, and to sing lustily a la 1908 vintage, possibly with gentle swaying and fraternal hugs / arm linking. (It's a bit like the Sign of Peace - but in the cathedral of baseball instead of a church). Also be prepared for some celebrity to louse up the anthem.
Here's a Covid-safe version for now.
Take me out to the ball game Take me out with the crowd Buy me some peanuts and crackerjacks I don't care if I never get back Let me root, root, root For the home team If they don't win it's a shame Aahh For it's one, Two, Three strikes you're out At the old ball game