[交流] Funny English quiz in everyday（NO.8）

Previously
Q: The ages of a father and son add up to 66. The father’s age is the son’s age reversed.How old could they be?(3 possible solutions, you have to answer all-around)

A: 6,60/24,42/15,51.

Today’s Question
What is easy to get into but hard to get out of?

We will hold this column everyday, the one who write the right answer first can earned 1 BB.
If u missed it this time, please come on and come here early, then use your smart head to find the answer.
I will give u the right answer in the column tomorrow.
So good luck to u!