？
Wanna go on a bus tour next Saturday?
Literal
Next-week Saturday [on-に] bus-tour [object-を] do-not?
~ない? (plain negative + rising intonation) is a casual invitation — 'won't you do X? / wanna do X?' Functionally similar to ~ましょうか but much more casual. バスツアー is a katakana compound loanword. Between friends.