(Requires the Seasons expansion pack)

If you have the Seasons expansion pack you can add “Smoking Weed” as a holiday tradition. At last you can create your Sims 420 day.

If you want to create a 420 day, create a custom holiday in the calendar, call it 420 and add “Smoking Weed” as a Holiday Tradition.

Smoking and eating edibles counts towards finishing the days goal.