Pendejo means stupid.
Uh, not quite. It is a complex term, being slang, and PART of it may mean stupid. Other people look at it as being stronger than calling someone "a--hole" in English.
Jeb knows what he's doing - at least with that word. Trouble for him is that he's really not winning any new votes among the invaders, but he is really showing what a pendejo he is to those of us who actually care about this country. IOW, he is doubling down on being a pendejo.