The phrase "up ears" refers to the act of listening attentively or paying close attention. There are many synonyms for this phrase, including pricking up one's ears, tuning in, being all ears, listening intently, giving someone your undivided attention, honing in on, paying heed to, and being responsive. These synonyms convey the same meaning of actively listening and being engaged with what is being said or heard. Using synonyms can add variety to one's writing or speech, and help to convey a clearer and more precise message. Ultimately, the ability to perk up one's ears and listen intently is a crucial skill for effective communication in any setting.