Rosmerta is already a happy, cheerful person. But today? Nobody's personal boundaries exist for her! Everyone should be prepared to be hugged enthusiastically and friends will get sloppy kisses on the cheeks and forehead.
Alex is far too distracted by everything to pay too much attention to any one thing at once. While he's always talkative, today he's probably pretty incomprehensible, not able to finish one sentence before he's on another. Also, everything is the funniest thing he's ever heard.