Symbols for monkey bars, swings, slides, and seesaws, which are common in the storyknifing we observed, of course, were not drawn before such articles were introduced into the culture with the building of schools and playgrounds in the villages. The use of the symbol or the word "yes" to signify the end of a storyknifing session was not used by the women in Margaret and Leota's generation.
Source: wiktionary