"걸" is short for "것을", and "것" is used to nominalize verbs.^^/ In spoken, "거" or "게" is more often used in place of "걸" without the object particle "을". (In spoken, object particles are often omitted^^) to do = 하다(a verb) 하는 것 = doing (nominalized) 하는 것을(object) = 하는 걸 = 하는 거 = 하는 게 (것을 ☞ 걸 ☞ 거, 것이 ☞ 게) to cook = 요리하다(a verb) 요리하는 것 = cooking 요리하는 것을(object) I love cooking = 나는 요리하는 것을 좋아한다.(just a statement) = 난 요리하는 걸 좋아해. = 나 요리하는 거 좋아해. = 난 요리하는 게 좋아.("게" is the contraction of "것이") \^o^/

sorry i didnt mean to comment it was an accident

http://parksguide.blogspot.com/2009/06/i-like-doing.html