Although carbonated beverages can sometimes cause a human's eyes to water, this girl is actually emotional about drinking Pepsi for the first time.
According to the YouTube description, the woman in the video is allergic to caffeine, which prevents here from drinking most popular soft drinks. So her boyfriend Mario purchased her a bottle a caffeine-free Pepsi.
"What's wrong?," Mario asks his girlfriend after she takes a swig straight out of the bottle and places her head in her hand.