The Collaborative International Dictionary of English v.0.48:

Blub \Blub\, v. t. & i. [Cf. Bleb, Blob.]
   To swell; to puff out, as with weeping. [Obs.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

blub
    v 1: cry or whine with snuffling; "Stop snivelling--you got
         yourself into this mess!" [syn: snivel, sniffle,
         blubber, blub, snuffle]