Something you made earlier, usually refers to a spliff or reefer, where you have made one at some other time and are now ready to smoke it.
Can also refer to cookery.
Ah look, I've found a blue peter, what a top do. It's ok I've made a blue peter.
Someone who is as numb as the day is long. When said person makes a stupid error no one else would ever do, or admit to anyway.
"You Numpty" you've just run over the cat!. The shear numptyness of the man was unbelievable.