Justin Bieber Goes on Titanic Date With Selena Gomez

Sources connected to the Biebs tell us .. Justin hatched the idea after seeing the movie "Mr. Deeds" -- where Adam Sandler surprises Winona Ryder with a date at Madison Square Garden.

Here's how it went down tonight ... Justin took Selena to the Demi Lovato concert at neighboring Nokia Theater. He then said, "Come with me" -- and took her underground to Staples Center to watch the biggest shipwreck of all time.