What does "sweet cheeks" mean?

Doggypowerx
I got my wisdom tooth taken out yesterday which my boyfriend was aware about since I told him before I was getting it taken out. He told me he was going to get me some supplies that helped him when he got his taken out.

So today, he came over to my house to drop off the supplies which were pretty helpful. I hugged him and said thank you. When he left, I texted him "Thank you (:" and he said "Anytime sweet cheeks. Lolz" we've been dating for about 6 months now. I'm his first girlfriend.
What does "sweet cheeks" mean?
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