If you are a member of a scrum team you probably know this already. Once in a sprint planning session you define the complexity of stories.
Planning poker, also called Scrum poker, is a consensus-based technique for estimating, mostly used to estimate effort or relative size of development goals in software development. In planning poker, members of the group make estimates by playing numbered cards face-down to the table, instead of speaking them aloud. The cards are revealed, and the estimates are then discussed.
By hiding the figures in this way, the group can avoid the cognitive bias of anchoring, where the first number spoken aloud sets a precedent for subsequent estimates.
With this application you can have cards always at hand. You can select any card to show while playing planning poker. You can even show "coffee" icon, when you think there should be a break.