We analyze how overconfidence is affected by superstitious beliefs and emotions induced by positive and negative stimuli in a field experiment involving about 700 Italian students who were randomly assigned to numbered seats in their written examination sessions. According to widespread superstitions, some numbers are considered lucky, while others are considered unlucky. At the end of the examination, we asked students the grade they expected to get. We find that students tend to be systematically overconfident and that their overconfidence is positively affected by being assigned to a lucky number. Interestingly, males and females react differently: on the one hand, females tend to expect lower grades when assigned to unlucky numbers, while they are not affected by being assigned to lucky numbers. On the other hand, males are not affected by being assigned to unlucky numbers but expect higher grades when assigned to lucky numbers.