The term "most titillating" refers to something that is highly stimulating or exciting, often in a sexual sense. Accordingly, antonyms for this phrase might include words that convey the opposite of titillation, such as "boring," "dull," "uninteresting," or "monotonous." These terms suggest a lack of excitement or stimulation, which is the opposite of the high level of arousal that one might feel when encountering something titillating. Other antonyms might include words that suggest hesitation or reluctance, such as "timid," "shy," or "unadventurous." Whatever the antonym, it will convey a sense of the absence of the excitement and stimulation inherent in something genuinely titillating.