The phrase "be on tiptoes with curiosity" is often used to describe someone who is extremely interested in or curious about something. However, there are several similar phrases that could be used to convey the same sentiment. One such phrase is "be on the edge of one's seat" which suggests a sense of anticipation or excitement. Another phrase is "be champing at the bit" which implies a strong desire to know or do something. Lastly, "be itching with curiosity" connotes a sense of restlessness or eagerness to satisfy one's curiosity. All of these phrases serve as effective synonyms for "be on tiptoes with curiosity".