1) If your professor makes an offhand comment about being out of a job next January, and feeling that his replacement is unqualified.
Really, this could describe a lot of people. But it’s worth noting that the presidential term ends next January, and Joe Biden will be replaced by Mike Pence, a man whose qualifications are considered questionable by some.
2) If, in the middle of their lecture, your professor tells an anecdote involving them and a friend from work named Barack Obama.
Given that the current US president is also named Barack Obama, and the president must often work closely with the vice president, this might indicate that your professor is actually the current vice president – Joe Biden. Granted, this work friend could be a completely unrelated Barack Obama, but it’s worth remembering.
3) If your professor performs his lectures in the White House.
Very few people operate out of the White House in a professional capacity, but Joe Biden does. It’s not necessarily a confirmation that your professor is Joe Biden, but it’s certainly a piece of circumstantial evidence.
4) If your professor occassionally rants about how they almost won the 2008 Democratic Party Primary.
There’s really only so many people that could meet this description. Unless your professor is Hillary Rodham Clinton or John Edwards, this means they are almost certainly Joe Biden.
5) If the questions your professor asks to the class include “who should be appointed to replace Supreme Court Justice Antonin Scalia,” or “should I close Guantanamo Bay?”
The appointment of a supreme court justice and the closure of a military detention camp are the kind of issues that a vice president may have to resolve – especially one from the United States, such as Joe Biden.