I drink a lot of sour beers. The agent of souring is generally lactobacillus or pediococcus bacteria producing lactic acid. The pH of these is generally around 3, which is a little bit higher than vinegar. I've made some homebrew that is a bit lower - though it ended up being ab it too sour for my personal tastes. There have been plenty of days where I have had more than 2 liters of sour beer - many commercial bottles are sold as 750mL, and sour beers are generally relatively low alcohol %, so it's easily possible to drink plenty of these if you've decided you want to make a day of it.

About the only ill effect would be some heartburn. Tums to the rescue