Planning poker is a way to estimate tasks in Scrum, during the sprint pre-planning. Tasks are estimated using story points, which are a relative measure of complexity, usually defined by taking a single, well-known story as a reference.
A simple answer might be: 1/2, 1, 2, 3, 5, 8, 13, 20, 40, 100, question mark (for I-don't-have-a-clue), and "coffee break" (for cafeine-might-help-me-focusing).
The non-linear nature of the deck values makes sense - because the larger an estimate gets, the smaller the significance is of the estimate. So, it prevents a sense of accuracy that really isn't there. You might want to ask yourself why the estimate is so large - maybe your story is too big. But let's not dig into that, this post was just about the card values.
