You may not have acetone on hand, but you may have a bottle of nail polish remover. Nail polish remover is formulated to take the enamel layer off fingernails, which is essentially what you're attempting to do with your car's finish. Any brand will work, and the higher the percentage of acetone, the better. Choose a terrycloth or microfiber towel so that you don’t scratch the clear coat or paint on your car. You’ll want to keep the cloth wet at all times, so if it starts to dry out, add more acetone or nail polish remover. Wear gloves to protect your hands from the acetone or nail polish remover and paint transfer. Use small, circular motions to remove the spray paint from your car. Rub very gently, or you risk removing the clear coat or the paint on your car, rather than just the spray paint. The paint will transfer from your car to the cloth, so switch out your cloths often. You’ll want to thoroughly wash and rinse your car after removing the spray paint. Pay special attention to the spray painted area to get rid of all traces of the paint as well as the acetone or nail polish remover.

TL;DR in Vietnamese:
Mua một chai a-xê-tôn hoặc dung dịch tẩy sơn móng tay có chứa a-xê-tôn. Rót a-xê-tôn hoặc dung dịch tẩy sơn móng tay vào khăn vải. Nhẹ nhàng lau lên vết sơn xịt. Rửa xe sau khi làm sạch sơn xịt.