In Plague Inc., you can name a disease after anything you like and make it wreak havoc on Earth's population. In the days since the U.K.'s decision to leave the European Union, the event has become players' top choice for naming their plague.
"Brexit" has taken the No. 1 spot from "Trump," which has retained popularity for the last few months. According to developer James Vaughan, "Brexit" seems to have already reached its peak, whereas "Trump" has remained constant.
Vaughan stated this type of timely response is typical for Plague Inc. For example, around the time of the 2012 presidential election, the name "Obama" saw a spike in prominence. As actual epidemics like Ebola and Zika break out in the real world, they become popular choices in Plague Inc. as well.
It should be noted that the popularity of a plague name does not necessarily link to negative connotations. Vaughan pointed out that players will often name diseases after their boyfriend or girlfriend, for example. Of course, how upset players were with their significant other at the time of their game session is not something that's tracked as easily.