This dare can be as easy or hard as you want it,
First go to
https://www.teamup.com/ and create a calender
Then set out you're regular day to day activities, e.g. Working out, Working, Pre-planned events
You can either choose whether you want people to be able submit tasks any time you're busy or you can make time slots where people can submit tasks(make most of the day an event/busy and leave spaces where people can submit tasks/dares)
Remember to save Admin Link somewhere
Next go to options and click sharing. Select "+New link" (top right) and select the following options,
Name: Whatever
Active: On
Admin: no
Calendar: Would recommend having operate calendar for dares
With permission: Add-Only (Important)
After that post that link on this post and good luck.
Example:
https://teamup.com/kspfiy2k1yiovnzveo