incasual language, is like 'あのこと', the 'thing'. I can't help but think of the relationship to the dutch student slang of 'jetser'.
Can be used for things, but also for people.
combined with あの、この、その
when combined with こそあど (ここ、そこ, あそこ, etc), it contracts!
このこと、この人 → こいつ (~~このやつ~~)
そのビール → そいつ ((~~そのやつ~~))}}
あの人 → あいつ ((~~あのやつ~~))}}