High five

The high five (also known as high tree or high one among various species) was a gesture of achievement or agreement in which one person slapped the upraised palm of the hand, about head-high, against that of another. Despite neither of them having proper hands, the astromech droid BB-8 and the loading droid F3-ZK once performed a high five together on Jakku.

Text and facts from the “High five” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.