What i think is that "bendeco" stands for the spanish word "pendejo" which means something like "asshole" using slang. Only that Cheech´s so fucked up that can´t proounce properly... fuma porros, petas, leños, macas, bengalas, lirios, cañones, trompetas, velas...
Yeah, I remember that saying from Cheech & Chong's Next Movie. Chong said that to a lady, she gets pissed off and everyone gangs up on their van - not the weed van.