From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Veku (ベクウ, Bekū) is the fat version of Gogeta.
Veku appeared when Son Goku and Vegeta attempted to fuse for the first time in Dragon Ball Z: Fusion Reborn. North Kaio blamed Vegeta for the mistake by claiming that Vegeta had failed to extend his index finger, resulting in an embarrassingly weak Fusion. This formed a fat, incredibly weak fighter who was called Veku by South Kaio. In this form, speed was decreased and ki was extremely limited. Veku was unable to perform any special ki attacks due to the severe ki limitation. Also, because of his fat body, he could not retaliate by punching and kicking. Instead, all he could do was pass gas, which he used against Janemba to try and escape him. Like most fusions, there was a 30-minute time limit before the two fighters defused.