The lock code in Dan’s Diner on Roblox is 03-29-08. That code appears in multiple player guides and wiki references for the hatch/door puzzle in the game.

For the other related doors, common hints are:

  • “Creator and Destroyer”
  • “Confronting problems is often the best solution”
  • “Creator of life”

If you want, I can also list the full sequence of Dan’s Diner puzzle codes in order.