Be Like Bill is a 2015-2016 meme is a raging virus: It has propagated faster than any other internet meme.
Bill is a stick person illustration, with white space left for captioning. The version pictured here is the Bill with the hat/toque headdress. You will also see versions of stick person Bill sitting at a computer.
The irresistible appeal of Bill is that it is a powerful passive-aggressive way to make public judgments about other people's life choices. If you want to comment on something you disagree with, the innocuous Bill stick figure is an excellent vehicle to transmit your message.
In the same way that Kermit and his teacup have become a tool for highlighting and criticizing others, Bill is a wildfire hit with anyone who wants to feel morally superior to others.