Sweet Tooth is quite obviously a metaphor for whatever it is that gets the character high but is probably detrimental to his health, as referenced by broken hearts and cavities. Drugs in this case are the most likely… because he talks about taking the “tube ride” if he pleases. This is referencing snorting cocaine through a tube as is usually done. Also the line that he is a savage in the basement…where this kind of stuff probably usually happens. Then he gets high and loses his inhibition, willing to “fight in a strangers home with tchotchkes,” and “roaring like a feline (or lion).” Soon he gets higher than the trees, and keeps on climbing, as stated by being on an incline, and holds hands with cosmic entities (how else could this be done?). He also describes the need for more as is typical in drugs as the body becomes more and more resilient to the drug(s). He stops caring about being kicked out because he is so high he just doesn’t care. A helicopter by a stop sign becomes a strobe light as a result of the high. He describes being on another plane of existence, which the high creates, another result of the drugs. The crazy eyes being another effect of the drugs as they realize he was never invited in to join and is most likely getting his fix at another’s expense, any way he can. The the chorus plays and finally he mentions being unable to regularly find an escape from reality by the line “I can never find a refuge,” and he’s a “little cuckoo” for the drug cuz he’s always had a “Sweet Tooth.”