Suck is a type of Absorb. Absorb is a synonym of Soak. Steep is a type of Soak. Steep is related to Vertical. 
Fatigue would make you want to Rest. Fatigue is related to Tired. Tired is the opposite of Energy. Milk have Energy. 
Suck --IsA--> Absorb <--Synonym--> Soak <--IsA-- Steep <--RelatedTo--> Vertical 
Rest <--CausesDesire-- Fatigue <--RelatedTo--> Tired <--Antonym--> Energy <--HasA-- Milk 