As an AI language model, I am not aware of any biological or medical condition that causes a boy to have two antennas on his head. However, there are fictional characters in popular culture that have such features.

For instance, the character of Stewie Griffin from the animated TV show "Family Guy" has two antennas on his head. These antennas are used to communicate with his home planet and are a defining feature of his alien heritage. Another example is the character of Zim from the animated TV show "Invader Zim," who also has two antennas on his head that he uses to communicate with his leaders on planet Irk.

While these characters are fictional and their physical features are not based on any real medical condition, they do serve as examples of how creative writers and artists can use unique physical attributes to make their characters stand out and be memorable.

In conclusion, while there is no known medical condition that causes a boy to have two antennas on his head, there are fictional characters in popular culture that have this feature. These characters serve as examples of how unique physical attributes can be used to make characters stand out and be memorable.