visitors who are not familiar with the history and nature of such rivalries are best advised to avoid taking sides in any rivalry of this type, seeing as one can unexpectedly offend someone's feeling or set the tone for an unpleasant discussion.  

for the sake of keeping the atmosphere light and non-confrontational, as well as avoiding the faux pas of offending or annoying a local, it is generally best to stay clear of contentious and divisive topics. these can include subjects that are commonly understood to be contentious in many parts of the world, such as politics, religion, and wealth distribution.