I thought the implication was that they were going to use it to sexually assault her or make her submissive to them. (This manga is pretty dark, after all)
Though, it's always bugged me that in manga there's just a bunch of men that see a woman on the street unoccupied and smell blood in the water, and so rush instantly upon her. @XANA
It's a reasonable inference given the circumstances. (Two grown men approaching an underage girl they have no relation to asking her to 'hang out' with them...Heavily implies something bad is gonna happen, but its unlikely to be murder given that they're not likely to just kill a random girl for yeeting them) @Mnuchinboo