Why do girls post pictures of themselves where it is clear that they aren’t wearing anything and just cut the picture off right above their cleavage?

I’ve seen this from multiple friends of mine who would not normally post overtly sexual things but then post shower photos or their hair for a Halloween costume and if it was any lower would be NSFW because they aren’t wearing anything.

Updates
+1 y
To any girls who answer do you think it is weird or am I just being a guy and seeing sexy when it isn’t intended
Why do girls post pictures of themselves where it is clear that they aren’t wearing anything and just cut the picture off right above their cleavage?
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