Why is it considered bad manners to eat your peas with a knife?

says who????haha

Only the fork is acceptable in top British Dining Circles, the Knife is a definite No No.
Use the knife and you will not get invited back to top society Dinners.

The knife isn't considered acceptable to eat off for anything.. it's only to be used to cut food and to help push food onto the fork... Well that's the official version but of course, people can do as they please in their own homes or familiar company.. I like to think that the idea originally made sense as in knives can be sharp and it's a bad idea to put them into your mouth.. but who knows.

Once upon a time table knives were sharp and could cut your mouth. Now we eat meat that is so tender it can be cut with the fork.

Not as bad as juggling with them.

maybe cause youre making a mess that way

Because it would make you look like some kind of redneck who never owned a spoon or fork before.