They are playing on a peculiarity of the German language. An S at the beginning of a word, followed by a consonant is pronounced 'Sh'. If you watch old Top Gear, when Boris Becker was on as the Star in a resonably priced car, he kept referring to the Stig as - "ze Shtick".
A few short clips with the excellent Samantha Spiro: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Rd-zjvi1ErE.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-aFxxZHUL1fU.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-OpxflCJKntI.html
I'm from Reno. To give someone a Glasgow kiss, you headbutt them aiming your forehead for the bridge of their nose, hopefully breaking it (their nose, not your forehead).