Mweek

Mweek is one of Tweek's brothers that can be found in Dinos Upstairs.

How to Rescue
When you enter the Nursery, clear the area of enemies if necessary and leap up the building blocks. From here, glide over to the record player and flip the arm to change the track. The eggs will hatch, revealing three baby dinosaurs. Move back to the blocks and then onto the playset next to them. Walk up the top and leap onto the top of the basket. You can now jump or glide across the heads and onto the planes where Mweek waits.

Alternatively, you can just jump across the eggs - Though this is slightly more difficult.