This term derives from the last word of the famous blackletter-Gothic sign in mangled mock German that once graced about half the computer rooms in the English-speaking world. One version ran in its entirety as follows:

ACHTUNG!ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKEN.IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN.

This silliness dates back to least as far as 1955 at IBM and had already gone international by the early 1960s, when it was reported at the University of London's ATLAS computing site. There are several variants of it in circulation, some of which actually do end with the word blinkenlights.