Just so you know, regular vodka won't burn, at least not easily. You'd need high test moonshine or equivalent. Much better to use gasoline. If you get bored you could even play a little game by dissolving styrofoam in it.
As I've become older and been friends with many much older people, they generally take care to say something like "I really appreciated your help yesterday".
I don't know if it's right or wrong, but they're telling you they enjoyed the time/favor whatever.
It's just an incredibly bad look.