Check out this episode by mentalist Derren Brown https://www.youtube.com/watch?v=sEmCQzueyEQ where he sits down with the actor Simon Pegg and - from the description - "Derren convinces Simon Pegg that he wants a BMX bike for his birthday"
It's really fascinating what happens - how malleable the human brain is - and the video also goes through how Derren did it. Worth a watch if that stuff is interesting to you.