I would Not do it either, i have carefully selected the products i use and love them, if i wanted a tan somewhere else i would choose somewhere that used the same products as myself unless it was someone i knew well, i honestly think that she bought a large bottle thinking she could apply it like a self tan lotion or mousse and got a surprise when she realised the solution requires an air compressor, you cant apply that type of solution without one, i think if it were me i'd feel a bit used, i would maybe be sympathetic if she was honest with me though and owned up to the real reason