Rami's answer is perfect. A manbag is a type of bag that some men think look more suitable for a woman.

"Wouldn't be seen dead" is an informal expression. If someone "wouldn't be seen dead" in a particular place or doing a particular thing, they would never do it, usually because it would be too embarrassing: "I wouldn't be seen dead wearing a dress like that."

Hi there! Great question! Here are some examples: Situation 1: I'm a guy. A very macho guy. "I wouldn't be seen dead wearing a dress!" Hahahah.... or "I wouldn't be caught dead wearing a dress!" Funny, huh? Well, that's how we use it! :) Have fun learning English! DS3