Can Muslims throw a surprise party?

Keeping a secret is not lying

There's a big difference between not telling someone something and telling them something false. Islam asks believers to speak truthfully:

The Prophet ﷺ said that truthfulness leads to righteousness and righteousness leads to Paradise, while lying leads to wickedness (Sahih al-Bukhari 6094). He also joked with people, but he said, "Indeed I do not say except what is true" (Jami at-Tirmidhi 1990). So a surprise should be built on silence and discretion, not on false stories. See What does the Quran say about lying?

How to keep it secret honestly

If the guest of honor asks questions, you can stay truthful without spoiling it:

• "I can't tell you, it's a surprise."
• "Just keep Saturday evening free for me."
• "Let's go out. I'll explain on the way."
• Ask a friend or relative to bring the person along, so you never have to answer questions at all.

Avoid inventing elaborate cover stories, such as saying you'll be somewhere you won't be. Honest hints are less stressful to keep up and leave no one feeling tricked afterwards.

Don't give anyone a fright

A narration in Sunan Abi Dawud tells of a man whose rope was taken by a companion while he slept; he woke up alarmed, and the Prophet ﷺ said, "It is not lawful for a Muslim to frighten a Muslim" (Sunan Abi Dawud 5004). That applies to surprise parties:

• Skip loud jump-scares for anyone with a heart condition, anxiety or a history of panic attacks.
• Keep lights soft and the shout gentle: "Surprise!" rather than a crowd bursting out of the dark.
• Keep it short and kind, and let the person sit down and enjoy it.

The same rule applies to pranks on camera. See Is it haram to make prank videos?

Make the party halal-friendly

• Food and drinks: serve halal food and soft drinks or juice.
• Guests: think about whether the person would be comfortable with mixed company, especially if they're a hijabi sister who may not have her scarf on at home.
• Venue: a family home, a halal restaurant or a quiet garden works well.
• Occasion: a birthday, a new job, a graduation or an anniversary. These are fine as simple social occasions.