He was left at home by accident last year.
5 seconds sound clip from the Home Alone 2: Lost in New York movie soundboard.
You can hear this line at 00:22:07 in the Blu-ray version of the movie.
Quote context
[...]
- Has he ever been in a situation where he's been on his own?
- As a matter of fact, this has happened before.
- It's becoming sort of a McCallister family travel tradition.
- Funnily enough, we never lose our luggage.
- He was left at home by accident last year.
- Yeah, that's what my wife meant when she said it's becoming a McCallister family travel tradition.
- We'll call Chicago and notify them of the situation.
- The odds are that's where he is.
- Thanks.
[...]