The antonym for the phrase "frowning up on" can be anything that connotes positive emotions or actions. Examples of antonyms are "smiling upon," "welcoming," "embracing," "approving of," "encouraging," "accepting," and "supporting." When someone is frowning up on an idea or proposal, it means they are expressing disapproval or negativity towards it. In contrast, if someone is smiling upon an idea, it means they have a positive attitude towards it and are willing to support and encourage it. By choosing antonyms that convey positivity and acceptance, we can create a more conducive environment for creativity, growth, and innovation.