Green’s Dictionary of Slang

dripper n.2

(drugs) an eye-dropper, used to make a makeshift syringe or to drop LSD on to sugar-cubes, blotting-paper or some other medium of delivery.

[US] ‘Und. and Its Vernacular’ in Clues mag. 158–162: dripper Eye dropper used by drug addicts.
[US]B. Dai Opium Addiction in Chicago.
[US]Monteleone Criminal Sl. (rev. edn).
[US]Lannoy & Masterson ‘Teen-age Hophead Jargon’ AS XXVII:1 30: spike and dripper, n. A needle and a syringe.
[US]M. Braly Shake Him Till He Rattles (1964) 135: The middle pages had been cut to form a small box, and the dripper and spike were packed in old cottons.

In phrases

lip the dripper (v.)

(drugs) to use suction to remove all traces of air from the medicine dropper that is used as a makeshift hypodermic syringe.

[US]D. Maurer ‘Lang. of the Und. Narcotic Addict’ Pt 2 in Maurer (1981) 105/1: To lip the dripper. To suck all the air out of the dinghizen before taking a shot; addicts commonly test for air by getting the dropper to stick to their lip or tongue-tip.
[US]J.E. Schmidt Narcotics Lingo and Lore.