From what i know about boobs, other than that they feel like bags of sand, is that this is a side effect of pushing together boobs that just aren't there. Often when a girl has saggy boobs or the weird deflated tube boobs it is hard to display cleavage with a low top like a normal girl. If a girl has a large chest or a perky chest she can have her cleavage on display and it will look normal, with a simple line for large which are pushed together or two separate lumps with a fine gap in between them. The problem is when a girl lacks both and tries to display you get that look that you see above that i can't quite describe and it will really show with a line going down the center showing how they pushed them together.
Dickbutts body is a dick, with another dick attached to it... Titpussy's body is tits, with another set of tits attached to it... see where it's going?