At what age does breast feeding go from a little weird to really creepy?

I just saw a movie preview where a son comes from playing to breast feed off of mom. A guy asks his pal how old is his son and he says 48 months and his pal says that’s 4 years old. He was hoping 48 months made him seem more like a younger child.
It did make me chuckle but my point is at what age is it just beyond weird. If you are not from the US and breast feeding is pretty acceptable after 2 please let me know what country your from and at what age does it get weird? Does it become a psychological problem for the child after a certain age? Does it do more harm than good if the child becomes overly attached at a young age?