The phrase "whistling for" can be replaced with a variety of synonyms. A few of the most common alternatives include "calling for," "summoning," "beckoning," and "inviting." Other synonyms for "whistling for" include "hailing," "signaling," "requesting," and "demanding." Each of these phrases is commonly used to indicate that someone is trying to get the attention of another person or group. Depending on the context and tone of the situation, different synonyms may be more appropriate, but all of these options convey a sense of urgency or need to connect with someone.