bit of a silly name but can't come up with any serious information on it. According to the 2000 United States Census, recreational use of xylenol is on the rise. And it's popped up a few other places, but I can't find much information on it.
Xylenol seems to be a term like "phenol" or "cresol" - it's a class of organic aromatic compounds. I know related nitrophenols (2,5-dinitrophenol) can be "abused" sometimes as fat burners because they decouple ATP production. (generating heat & eventually even cataracts) I don't believe that it's recreational or abusable.
I think they are referring to xylene (sometimes xylol, it has a bunch of names), a volatile organic compound similar to toluene that is used as a solvent in industrial inks, glues, sealants etc. that can be inhaled for a stupourous narcotic effect. It is equally toxic (maybe a little less) as toluene but takes even longer to evaporate. It's used as a feedstock for PETE production. (pop bottles)