do on the sly

When Burnett was growing up in Brooklyn, dancing was something he had to do on the sly.

Instead he encouraged people to give, saying that if drinking "is the only happiness he has in life, that's OK. Instead, ask yourself what do you do on the sly? What 'happiness' do you seek in secret?"

“Instead, ask yourself what do you do on the sly? What ‘happiness’ do you seek in secret?”

But this, he said, very good naturedly, he was compelled to do on the sly, for though his customers were principally poor people, if it got noised abroad, nothing could save him from the fury of a mob of pious and very orderly people, who would get up town meetings and vote him down an intolerable nuisance.

"Well," said Meadows, "what you are, I am; what I do on the sly you do on the sly, old thirty per cent."