| Also forcing a dry entry might, in the case of sexual intercourse, cause tiny capillaries on either partner's gonads to burst, increasing chances of disease transmission, like AIDS infection, and also making the process generally less comfortable. To prevent a dry entry foreplay is performed since through stimulation, cells in the vaginal walls secrete a slightly acidic fluid which besides acting as a lubricant, also provide a mild resistance to pathogens. This lack of stimulation and in turn, lubrication, is what makes rape (excluding all psychological traumas of course) and tampon insertion painful.
So make sure you never force a dry entry, because besides mostly not being able to make an entry at all, if an entry is made it might be a rough one, causing pain. | 
