The Party Gabrielle Threw in his Tunnels
I'm trying to see how the kids explained to their parents where they were going. Even if they didn't mention that the party would be in a network of tunnels (and at least one of them would), it would just take one parent to recognize the name John Rambo.
"Hmmmm.....let me see. You want me to let you go onto the property of a guy who went crazy and butchered a town full of sherrifs deputies, so you can party in some network of underground survival tunnels he dug under his property?....I think you're grounded."
Remember the media didn't see first blood the way us the viewers saw it. To most people who remember the story he is a blood thirsty psychopath, and over time the number of dead deputies would get exaggerated.