Hello, would someone please tell me what's the meaning of "suck the fun out of ..."? Thanks!
Here, 'suck' = 'take', but with a slightly negative feeling.

The teacher's angry looks sucked the fun out of our teasing the little boy on the playground.

Your expression of feeling guilty sucks the fun out of our playing tricks on our friends.
This is usually done by what people call a party pooper or debbie downer. Taking a great situation and doing something to change it quickly to the opposite.

A party pooper sucks the fun out of a lot of things.
definition of party pooper is
1) A person who ruins a party by either stopping the fun or not participating in a certain activity
2) A person that ruins a festive moment with their attitude.

Susan sucked the fun out of the party when she came into the room and immediately turned off the music. Susan is a definite party pooper.

Sharon was talking about Betty's great tan. Susan then quickly said, aren't you worried about the long term affects of the sun on your skin? All kinds of new reports have come out recently . Susan was definitely being a debbie downer.

also called sucking the life out of or sucking the air out of