hypergelast
Someone who laughs excessively.
America had become a laughing nation, a country of frivolists and hypergelasts, a culture dangerously out of control.
Where it comes from
From Ancient Greek ὑπέρ (hupér, “over”) + γελαστής (gelastḗs, “laughter”), from γελάω (geláō, “I laugh”).
Adapted from the Wiktionary entry hypergelast (CC BY-SA 4.0).