usually occurs when one is eating a sandwich at lunch that is filled with excess mayo
Allison: Hey Christina, I heard you pulled a guando yesterday at lunch.
Liz: Hey Christina, how did you get that stain on your skirt?
Christina: Well Liz, I pulled a guando at lunch.
"Bill asked Monica how she could be so callous as to not have washed the guando off of her dress."
"Man have you seen Danny De Vito recently? Man, that dude looks like a guando with arms and legs"