"He tried to thrust his war medals into my hands, [saying] 'take them back, give them back to the Prime Minister, I don't want them,'" before going into an aggressive spiel about Brexit, Allen told CNN.
Since the 2016 referendum, MPs have faced abuse on social media and in person for their stances on Brexit.
"Many of us in this place are subject to death threats and abuse every single day.
Brabin told CNN, however, that Johnson's language was helping "fuel hatred" and because anxiety is high among constituents, "the voice of panic and fear is heard louder."
"I don't think it's just Brexit," Allen said.