Via this Washington Times article:

Sen. John McCain is famously superstitious — he won’t take a salt shaker from a passer’s hand: bad luck

…

McCain has a whole slew of superstitions and rituals, many stemming from his days as a Navy fighter pilot, a notoriously superstitious bunch. He won’t throw a hat on a bed (bad luck), and he carries a lucky feather, a lucky compass, and a lucky penny — and nickel, and quarter.

…

Other presidents have been superstitious: FDR also suffered from triskaidekaphobia, inviting his secretary along if a dinner was to have 13 people and never traveling on the 13th day of a month (he’d depart at 11:55 p.m. on the 12th if necessary).

Reagan always had a lucky coin and gold charm in his pocket, knocked on wood often, never walked under ladders and tossed salt over his left shoulder when he spilled some (McCain does that, too). He and wife Nancy admitted reading syndicated horoscopes.

Good to know “important” people have their priorities straight. As an aside, I like to knock on wood too, I blame that habit on my wife