LWYDYLJ

LWYDYLJ is short form or the abbreviated version of Look what you did you little jerk

Made famous by "Uncle Frank" in Home Alone (1990), Kevin pushed Buzz and a commotion lead to spilt milk, wet passports, a squished cousin Fuller and soda on Uncle Frank's pants. Look What You Did, You Little Jerk is the expression used after Kevin ruined everything.

LWYDYLJ because you're a little bitch and had a tantrum, you spoiled the good time for everyone.