Custom is a synonym of Habit. Habit is related to Drinking. 
Guarantee is a synonym of Ensure. Ensure is a synonym of See. See is related to Shadow. Shadow is related to Black. 
Custom <--Synonym--> Habit <--RelatedTo--> Drinking 
Guarantee <--Synonym--> Ensure <--Synonym--> See <--RelatedTo--> Shadow <--RelatedTo--> Black 