He is not only a Congressman, but the Congressman elected and reelected from my district.
I have not personally met him, but both of my parents have spoken with him.
For a while he rented a local Congressional office on the same hall and in the same building where my dad worked. The thermostat that controlled the heat/air conditioning for my dad's office was in his office, which causes some disagreements. The staff was accommodating when he was in DC, but when hen the congressman was in town he liked to keep it around 85 degrees Fahrenheit in the winter and around 60 in the summer.
The reason I dropped my Political Science class the first time was because there was a project where we were supposed to interview a congressman, and I chose him simply because I thought it would be really convenient. His office never returned a message though.
He succeeded Cynthia McKinney, who was about equally eccentric. She was probably the most outspoken of all the "9/11 Truthers," who insisted that George W. Bush was personally involved in planning the destruction of the World Trade Center. This is despite the fact that some of her own biggest campaign donations came from Saudi Princes who also donated to Al Qaeda. Hank Johnson got elected the first time with a lot of help from Jewish groups who were upset at some rather anti-Semitic statements McKinney made. He was the first Buddhist elected to congress. After McKinney was defeated, she left the Democratic party to become a Green Party presidential candidate.
There is some pretty heavy gerrymandering going on here. Georgia's 4th district is one of the most strongly Democratic districts in the nation, so there is essentially zero chance of any Republican defeating Hank Johnson no mater what he says or does. He'll only ever have to worry about Democratic challengers during the Primary election. The voters of South DeKalb country really like there eccentric Democratic incumbents. McKinney only ever lost when large numbers of Republicans from my neighborhood crossed party lines specifically to get rid of her (Johnson had to pretend to be a lot more conservative than he really is when campaigning in North Dekalb), which they would only do on mass when there was nothing important going on in the Republican Primary.
After the 2010 census my neighborhood was moved to the staunchly Republican 6th district, so he is not my representative anymore. This also improved his odds of continuing to win reelection.