A tam o'shanter was a type of hat.
The Fourth Doctor once donned a tam o' shanter during his first encounters with Zygons during their Skarasen gambit in Scotland. (TV: Terror of the Zygons [+]Robert Banks Stewart, Doctor Who season 13 (BBC1, 1975)., PROSE: Time Lord Style [+]Paul Lang, Doctor Who The Official Annual 2024 (Penguin Group, 2023).)