Bewildered shoppers witnessed their first flash mob event when a large crowd gathered in Oxford.
The group congregated outside the Bridge Of Sighs, cheered and then dispersed after 30 seconds about 1300 GMT on Saturday.
Flash mobbing organiser Leo Hunter described the event as a "success".
Cities such as Birmingham, Manchester and Leeds have already experienced the craze.
The first event was reportedly held in a department store in New York.