红票 can refer to a discounted ticket or coupon, or to a traditional-style invitation ticket. Note that the pinyin given here is gōng for the first character, which is a non-standard reading — the standard reading of 红 is hóng. In this usage, 红 (gōng) is an old or dialectal reading, and the word is not common in modern standard Mandarin. You may encounter it in historical or regional contexts.