Guy leaning into me?

Guys do you ever sit really close to and lean on/lean into girls - and why? My female friends do this to me sometimes and say I'm comfortable to lean on haha but guys don't except this one friend. He squashes himself against me or leans into me or uses my legs (shins) as a pillow or similar and will adjust his shoulder or whatever so I can sit closer to him as well. Once I wasn't thinking and put my chin on his shoulder to watch something and he actually (I think) adjusted to let me be closer.
What would be your reasons for doing this? Would you necessarily like the girl?
Thanks!
Guy leaning into me?
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