New York CNN  —  The 10-second video begins with a close-up on the abs of a sweaty, shirtless man wearing low-slung, gray sweatpants. But three seconds in, it cuts to a panoramic video of Havasu Falls in Arizona, with its striking turquoise water cascading down from red rocks. Welcome to ParkTok. The video — from an unofficial account posting about Grand Canyon National Park and other nature sites in Arizona — is emblematic of a trend that’s gone viral on TikTok in recent weeks that pairs