This would be very difficult, if not impossible. Both colds and flu are transmitted in a similar way - through infected droplets in the air, or by touching a surface that has been contaminated by the virus.

Breaking wind does not expel drops in the same way that sneezing does, or even breathing. Quite apart from the fact that the person would usually have clothes on - and in most cases the source of the wind shouldn't be all that close to your face! - there is just not the substance being emitted that would make transmission of the virus at all likely.

So you probably don't need to worry too much about this one. The best way to avoid catching or transmitting colds and flu is still to avoid too close contact with people who are coughing or sneezing - and generally, you are less likely to suffer from infectious illnesses if you are fit and healy.