Bird-arse (noun) : a bird-arse is a person that is attracted or has a fetish for women/men with an ass as small as that of a bird.
Someone that is so lazy that they sleep, eat and take a crap in only one room.
Mark: hey dawg that girl got a fine ass.
John: man u are such a bird-arse, that girl has a tiny ass.
Max has been in his room foh da whole week, he is such a bird-arse.