UK sex-toy retailer Lovehoney allowed researcher Jon Millward to data-mine its huge database of over 1,000,000 sex-toy purchases and 45,000 reviews, in order to see what he could infer about Britons' sexual proclivities from the things they bought.
Millward worked with a supposedly de-identified data-set, though this is an extremely controversial subject in privacy research — he got first names and order-details, which seem to be difficult to re-identify. In any event, the conclusions he drew, which only work with aggregated numbers and stats, are definitely de-identified. Millward was able to compare the overall data to a smaller set from 60,000 of Lovehoney's reviewer community, which includes gender, marital status, sexual orientation.
Millward focuses on the anal toy category at some length, as it's both a taboo subject and a hot retail category, suggesting that there's a lot behind bedroom doors that we don't talk about.
Men do in fact buy larger dildos at a higher rate than women. The graph on the left shows that dildos under 7.5 inches long are bought at a higher rate by women than men, whereas those over 7.5 are more popular with guys. This isn't a function of sexual orientation, either.
35% of single straight men buy a realistic dildo that is 8 or more inches long (as do 35% of single gay men), compared to 30% of attached straight men, 25% of single straight women and 20% of attached straight women.
Men also buy large butt plugs at a much higher rate than women. Single straight guys are almost five times more likely than single straight women to buy a large butt plug and 76% more likely than attached straight men. Butt plugs with girths of 8 or more inches (which is as thick as a coke can) are bought by 1.8% of women who buy butt plugs, compared to 6.6% of men.
It seems that men like bigger dildos and butt plugs than women, regardless of their relationship status or sexual orientation. But if we're talking about big, you ain't seen nothing yet.