Meaning:
“婉” is short for “委婉” (wěiwǎn, meaning “politely, not bluntly”), “拒” means “to reject,” while both “了” and “哈” are auxiliary words that imply an easygoing and polite attitude of the speaker. Translated as “I will politely say no to your offer,” this line was reportedly first used by a public relations representative to refuse a journalist’s offer to interview a senior official of his company. Chinese netizens find the usage direct but not offensive and think it a good way to refuse people’s offers.
Example:
A: 我这周三晚请同事们吃晚饭，你也来吧？
Wǒ zhèzhōusān wǎn qǐng tóngshì men chī wǎnfàn，nǐ yě lái ba？
I’m planning to invite some colleagues to dinner this Wednesday evening. Would you come along?
B: 不巧我有远方的朋友出差来本市，约好了周三晚见面。婉拒了哈。
Bùqiǎo wǒ yǒu yuǎnfāng de péngyǒu chūchāi lái běnshì，yuēhǎo le zhōusānwǎn jiànmiàn。Wǎnjù le hā。
It happens that a friend of mine from faraway is on a biz trip in town and we’ve decided to meet Wednesday evening. Sorry I cannot come to your dinner.