Your co-worker seems to have a weird imagination. As pdq points out, it is a simple, straightforward song about lonely country girls longing for the bright lights where the diesel roadtrains are headed. This is how I hear it:



LONELY GIRLS
(Ian Tyson/Sylvia Fricker)

Instrumental intro

Light there is golden in the evening
Blue shadows forty feet and more
When night comes rushing fast 'cross the flatland you'll see
Lonely girls linger by the door
Lonely girls linger by the door

Linger and listen by the doorway
Lookin' down along the fence post line
To the highway beyond where the headlights roll on
Followed by a low diesel whine
Followed by a low diesel whine

Diesels' siren song of the prairies
Has a strong pull that never lets go
Diesels sing of bright spots with colours running wild
Follow me where the evenings overflow
Follow me where the evenings overflow

Instrumental break

Light there is golden in the evening
Blue shadows forty feet and more
When night comes rushing fast 'cross the flatland you'll see
Lonely girls linger by the door
Lonely girls linger by the door

Linger and listen by the doorway
Lookin' down along the fence post line
To the highway beyond where the headlights roll on
Followed by a low diesel whine
Followed by a low diesel whine

Source:   transcription from Ian and Sylvia 'Play One More' reissued on disc 3 of The Complete Vanguard Studio Recordings 4CD box set Vanguard 496/99-2.

--Stewie.