I won't address your particular example (“guys like drawing dicks on things”), but a similar one that I'm sure strikes you as cultural as well: the sex difference in toy preferences and play behaviour. The following is an excerpt from the book Perspectives in Male Psychology by Louise Liddon and John Barry, which argues that it's not subcultural:

“Some of the most intriguing evidence supporting the biological basis for sex differences in toy preferences comes, unexpectedly, from animals. There is a large body of evidence in animal research finding strong effects of prenatal and perinatal exposure to sex hormones on a range of sex-related behaviours, including juvenile play (Meyer-Bahlburg et al., 2004). Even more intriguingly, some research has found that male monkeys spend longer than females manipulating toys that move (wheeled toys or a ball), whereas female monkeys make more contact with a doll and cooking pot (Alexander & Hines, 2002; Hassett et al., 2008). Most intriguing of all is research that finds a sex difference in how primates play with objects: young females tend to play with objects as if they are nurturing an infant, and young males play with the same objects with more vigour, often as a weapon.

Compelling evidence for a biological basis for play behaviour comes from a 14-year study of ‘stick-carrying’ in Ugandan chimpanzees (Kahlenberg & Wrangham, 2010). These chimps tend to use sticks to signal aggression, to find food (e.g. taking honey from a hole), during play or as ‘stick-carrying’. This latter behaviour accounted for about 40% of stick-related behaviour, and was initially puzzling for researchers. The behaviour was observed to be most common in juvenile females, compared to weapon use, which was most common in males. The researchers noted that stick-carrying sometimes involved cradling of the stick, and the behaviour always occurred prior to the female’s first birth and ended when the female became a mother. The researchers concluded that stick-carrying is a form of play-mothering. The sex difference in stick-carrying appeared to be spontaneous and without any teaching by adult chimps, making social learning an unlikely explanation.

The overall explanation for the sex differences observed in these various human and non-human animal studies is that, in general, males are naturally predisposed to activities such as hunting and building, and females are naturally predisposed to nurturing the young (Hines, 2005). Extrapolating this evidence to humans, when boys are playing with cars this could be an expression of an innate tendency to track moving objects, as might be done in hunting, and when girls play with dolls this could be an expression of an innate tendency to nurturance and mothering.”