This is a sentence I've come across while reading 7 Things About Love That Make No Sense
If you’re the couple that just stands on the sidewalk for extended periods of time and boops noses together in between makeout sessions and sweet nothings, you deserve to get breadcrumbs thrown at you.
Is a metaphor or some rhetorical device used? Why do they deserve breadcrumbs? What are boops noses and sweet nothings?