Could he "of" or could he "have" come from Mars? 🚀

A mistake which is becoming all too frequent these days, particularly on social media etc., is for people to say they “should of” rather than “should have” done something. So when my grandson (7yrs) was chattering about time travel, a subject with which he is currently completely obsessed, he said something like ”I could of come from Mars…” my son and I simultaneously jumped down the little chap’s throat to correct him “no, it’s not OF, you should have said I could HAVE come from Mars”. Of course, my son and I just collapsed in fits of laughter at the ridiculousness of what we had both just said. 😏