The "ヽ( ’∀’)ﾉ┌┛三┌┛" emote is a representation of a person raising their arms in excitement or celebration, often used to express happiness or victory. It can be translated as "yay!" or "woohoo!". The "yay, a slide" emote is likely a variation or interpretation of this expression, specifically referencing the feeling of joy and excitement one might have while sliding down a playground slide.