I've only done that to a couple of ladies, where it just sort of happened rather than being the result of a specific request...an enjoyable (if at first alarming!) diversion.
Tiddlers: a very wise lady once said: "I looove men with small ones- they try soooo much harder!". Anatomical note: all that is necessary for successful penetration/impregnation is ca. 10cm (<4in)- look at the Japanese, they're not exactly becoming extinct. A female friend once told me that she and her friends were excited by the IDEA of a monster, but the reality was a good deal less fun (been there before, haven't we all?).