To be on the sly, the active of sly. You can do something on the sly, maybe stealing something funny and legendary, like mine and Jimbo's road bollard. You could also have 'slying it'
"We took that bollard on the sly"
"Tonight we're slying it/on the sly"
"Come on lads, here we go, on the sly on the sly"
Covert flirting between two people. Because they have to keep their true feelings for each other secret, for whatever reason (i.e. they work together, one is married, etc.).
"Those two can't seem to stand each other! They're always fighting over something!"
"Wrong, man. It's all a front they put up. They're actually macking on the sly."
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. PenguinBooks,1992. p. 38)