Mate is a synonym of Couple. Couple is a synonym of Item. Item is related to Key. 
Dear is related to Expression. Expression is related to Shock. Surprising can be used for Shock. Surprising can cause/lead to Funny. 
Mate <--Synonym--> Couple <--Synonym--> Item <--RelatedTo--> Key 
Dear <--RelatedTo--> Expression <--RelatedTo--> Shock <--UsedFor-- Surprising --Causes--> Funny 