Is it ensure, insure, or assure?
1580s, "elderly rustic," apparently a contraction of godfather (cf. gammer); originally "old man," it was applied from 1841 to foremen and supervisors, which sense carried over 20c. to "electrician in charge of lighting on a film set."
An exclamation of disgust; yuck
[1990s+; perhaps imitating vomiting]