The Rice University Neologisms Database

Etymology : A compound of ‘dab,’ a slang term for cannabis concentrate, and ‘pen,’ referring to the shape of the device. This term may be formed in analogy to the term ‘vape pen,’ meaning pen-style electronic cigarette, in which case the component ‘dab’ of ‘dab pen’ may be the verb for inhaling cannabis concentrate smoke or vapor rather than the noun for the substance. Though ‘vape’ also exists as a noun and verb-noun compounds are less common in English than noun-noun compounds, the component ‘vape’ in ‘vape pen’ seems to be a verb since the noun ‘vape’ would already refer to the device without the addition of ‘pen.’