'To get hitched for half a monkey' is to do something or to have something done for a bargain (literally taken, it means to get married for just 250 pounds, which is dirt cheap)
What?! Fix your loo for 5 quid? Why do you always want to get hitched for half a monkey?!
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.