The most popular slang expression of the day is "to rubberneck," or, more concisely, "to rubber."
"America To-day, Observations and Reflections"
William Archer
No, I think I'll take those few days off and do a rubberneck trip around Manhattan.
"Out of the Air"
Inez Haynes Irwin
I had myself noted that while the tall buildings here excited no curiosity in him, he acted as the veriest rubberneck under the clang and roar of the overhead trains; and the din of Broadway, he confessed, gave him vertigo after the soft tide of traffic that moves broad and full- 'strong without rage, without o'erflowing full'-down Tottenham Court Road, embanked with antique furniture or colourable imitations.
"Foe-Farrell"
Arthur Thomas Quiller-Couch