A 'smash burger' is a style of burger where a ball of beef is pressed flat ('smashed') onto a very hot griddle, creating a thin, crispy patty with a deeply browned crust. Originating in American diners in the mid-20th century and popularised globally in the 2010s via Shake Shack and TikTok. If your teen is talking about smash burgers, they are talking about food. Harmless culinary vocabulary.