Let in for
Definition 1 of 1
Pro Tip 1/3Unexpected Outcome
Indicates entering into a situation with unforeseen consequences or challenges that weren't initially apparent. 
I didn't expect so much work when I agreed to help; I really let myself in for it.
Pro Tip 2/3Colloquial Usage
Common in casual, informal conversations rather than in formal writing or speech. 
At the reunion, he let himself in for an evening of tedious anecdotes.
Pro Tip 3/3Personal Responsibility
Often reflects a personal choice that leads to unexpected difficulties. 
She let herself in for a world of trouble when she chose to foster four puppies.