It was the drawing of a "A nice day on the beach"
They say this:
"The administrator who deleted your deviation added the following:
A member of staff has reviewed a report concerning this deviation and has determined that the character(s) depicted in a nude, erotic or sexually compromising situation are established as being under the age of 18 in their original context.
Official policy does not allow such depictions, so this deviation has been removed and should not be resubmitted."