"Dressing up as people is very boring," Lee pointed out. "You're walking around with a suit on saying you're Barack Obama and don't even wear a mask? Costumes are supposed to be flamboyant. Costumes are supposed to be exciting.
"You put a black suit on and you say you are Arsenio Hall? That's the dumbest thing I ever heard," Lee added. "I had a girl say she was going to be Flo from the [Progressive] insurance commercial. So she said she was going to put on a white baker's smock and that's it. That's not a costume."
He ought to know. Lee has more than 2,000 in stock in his store in the 7500 block of Frankford Avenue. We're talking everything from Elmo and Dora the Explorer getups that rent for $90 to sexy nurse costumes that sell for around $40. You can get all medieval here. Renaissance and Colonial, too.
The reason Lee's so good at selling this stuff is he's a character himself.
He's also a family man with traditional, old-school values. I always enjoy talking with him because he has an opinion about everything. For instance, last week he was all worked up about school kids who stand at busy intersections with buckets begging motorists for money.
And don't get Lee started handing out relationship advice. He's got plenty of that.
"People call Steve Harvey," said Lee, who once performed as a standup comedian. "I'm sitting right here. Why are black women not getting married the way white women are getting married? They're vocal, and a lot of brothers can't handle all that mouth. You've got to be able to handle all that mouth."
Yeah, he went there.
Lee's never timid about going where others won't for a laugh. It's an old habit.
Lee, 42, grew up in North Philly, the son of a man he described as so abusive that his family lived in terror, hiding out in shelters run by the Salvation Army and Women Against Abuse.
"The abuse shelter was fun because they had a little gym for us," Lee said, jokingly. "You couldn't go outside though, because your father [might be] stalking."
At George Washington High School, he was an average student, his mind preoccupied with all the turmoil in his family. "Am I going to be killed?" he would wonder. "Is he going to choke us to death in our sleep?"
After graduating in 1990, Lee went to work for the Social Security Administration at Broad and Spring Garden streets.
Government life wasn't for him.
"I used to work in a cubicle, and the only thing that saved me was I could look outside and see there's a big world out there," Lee recalled.
On a whim in 1996, he did a stand-up comedy routine for a local talent search - and was one of the top winners.
Another "aha!" moment also happened that year, after a family friend asked him to entertain at a kids' party. "I didn't want to be bothered with no 5-year-olds," Lee said.
But to appease his wife, he eventually relented and went out and purchased face paint, a clown costume and candy. The kids loved his routine, and Lee realized he'd stumbled upon a lucrative side hustle. After all, parents are willing to spend money on children's birthday parties.
"You're going to pay for Man Man and Lil' Money," Lee joked. "[Parents] will pay money for him. They'll say, 'I'm not going to pay my electric bill but he's going to have his party.'"
In 2000, he performed a stand-up comedy routine on "Showtime at the Apollo."
"I didn't win," Lee said. "I got beat by a singer. But I didn't get booed."
Back in Philly, Lee was also organizing Christian comedy shows with other comedians at the Keswick Theatre and the Independence Seaport Museum. He added magic tricks to his stage repertoire. Derek Lee, the entertainer, was in full throttle.
Then, in 2007, the owner of D&J Costumes died. Lee, who was a frequent customer, got a call: Would he be interested in purchasing the store?
Some of his government co-workers thought he was nuts, but Lee left to take over the store. (He still does the clown stuff, and he regularly auditions for game and reality shows, though he hasn't been chosen yet.)
"If you can't cry, you've got to laugh," he told me, when I stopped by his store one recent day. "I think that's why I didn't take life serious, because I was dealt so many bad cards."
The phone rang about then.
A woman wanted to know if Lee had a Captain America costume for rent.
Lee responded with a happy trill in his voice, "Yes, we do have Captain America. When is your party?"
Hanging up, he looked back at me and said, "This is a fun job. I love it. I really do."
On Twitter: @JeniceArmstrong