I've just opened up Blender to double check my answer... for science. At this point I'm just following my own curiosity but I'll post it in case it's at all useful.
So it really is like a pacman chugging a beer. The hard part is obviously not the flat part of the cylinder 'cause that acts the same as a cube. It's the curved part.
The intersection of two curved surfaces at these angles often seems to increase the curviness. What I mean is that if pacman were sucking a cube from these angles, the bottom jaw of the pacman would be a bit closer to a ) than a ⊃.
But from the lower angles it's a different story.
Then you get this double curve or S shaped curve. Could also be called the underboob curve. I think the process to follow for this curve it to think about the lines that would go around the curve and the cylinder, and then try to have them converge on a line in the middle. Like this: