The song is obviously about sexual tension and excitement, and is close to being X-rated but with clever use of metaphor to preserve the pretense that it might just be describing an actual fever. The speaker sees "rising possibilities" in the man (an erection, to be blunt), and his desire to "stay awake at night"--to have sex. "If I touch you I might get what you've got"--i.e., the same level of sexual excitement. 99.9 F is almost 100--suggesting he's in a state which is about to transition into something more complete--orgasmic satisfaction. He could be needing something cool against the skin--her body, whose touch can bring him over the edge and relieve the tension. Of course the metaphorical temperature works only in the imperial system: 37.9 C doesn't sound as much like it's on the edge of a complete change into something very interesting, while 99.9 C would be a lethal and impossible body temperature. 99.9 F, OTOH, is a plausible, uncomfortable but far from lethal, fever temperature, allowing the pretense that we're just talking about an illness...when this is clearly /not/ what we are talking about.
The song is obviously about sexual tension and excitement, and is close to being X-rated but with clever use of metaphor to preserve the pretense that it might just be describing an actual fever. The speaker sees "rising possibilities" in the man (an erection, to be blunt), and his desire to "stay awake at night"--to have sex. "If I touch you I might get what you've got"--i.e., the same level of sexual excitement. 99.9 F is almost 100--suggesting he's in a state which is about to transition into something more complete--orgasmic satisfaction. He could be needing something cool against the skin--her body, whose touch can bring him over the edge and relieve the tension. Of course the metaphorical temperature works only in the imperial system: 37.9 C doesn't sound as much like it's on the edge of a complete change into something very interesting, while 99.9 C would be a lethal and impossible body temperature. 99.9 F, OTOH, is a plausible, uncomfortable but far from lethal, fever temperature, allowing the pretense that we're just talking about an illness...when this is clearly /not/ what we are talking about.