Zway

təf-um bālä - to spit (EDG 592)

PWS
*tpp - to spit (SED I No. 72ᵥ)
Rather a biconsonantal stem with various ways of triconsonantization (*tpp, *twp and *tpˀ), Cf. *twb, *tbb ‘to spit, vomit’ (SED I No. 74ᵥ).