To be in a very intimate position with a love interest or sexual partner. Otherwise defined as obsessive PDA and doesn't belong in no damn environments, thank you very much.
Guy1: OMG, my girlfriend was totally straddling that prick, Josh!
When a woman mounts a massively THICK large cock or dildo and has her legs spread as far as she can, her pussy spread to its maximum width. Such an act is usually accompanied by seriously loud undulating moans from either pain or pleasure or both.
Tim: Christ, look at the size of that thing! How the hell can she take it all?
Chuck: Pff, chicks like that slut are used to straddling the dredgepipe. She could probably fit a 2 liter bottle upthat crack.