This is gonna sound weird, put the article of clothing in the freezer for about an hour, then see what luck you have getting it off. I LOVE silly putty, I used to buy two eggs a weekend for a little bit, I have like a 2 pound tub of it. After I freshly shaved my head I would smear the putty on my dome like a wig or something, Pretty Cool
I've successfully used the ice method for removing gum from hair, carpet and clothes (and we don't even like gum!). Here's a handy tip. Fill a ziplock bag with lots of ice then place the bag, not the ice, on gum spot. This keeps the area or item dry, greatly reducing elbow grease. Once frozen, use a straight edge, dull utensil to chip away gum. Some fabrics are more fragile than others so experiment first, sometimes it peels off easily. This could work for the freezer method, too, just put the item in a big ziplock bag. Gum is worse than blood, mud, and mustard combined. Bummer of a job!