Read the hints given in the riddle and guess the word.
You go in through one hole, you come out through three holes.
Once you’re inside you’re ready to go outside, but once you’re outside you’re still inside.
What is it?
Answer: A T-shirt.
The t-shirt has three holes: two sleeves and one neck. Once you are wearing the shirt, you are ready to go outside, but once you are outside, you are still wearing the shirt.