James Whale clashed with UKIP's Jonathan Arnott on his talkRADIO show, calling the MEP "a pillock" in a row over Gibraltar and his charity boxing debacle.
A series of high-profile figures in Britain have threatened war with Spain over Gibraltar, prompting mockery in the Spanish press.
James suggested Britain cannot justify its continued sovereignty over Gibraltar in the wake of Brexit, and asked why the UK should keep the territory because "we're leaving Europe."
Arnott said this was "incredibly disrespectful to the people of Gibraltar", adding that if Britain ceded the territory it would be "a disgusting betrayal."
This led to a row between the two, which culminated in James suggesting Britain should be given a referendum on whether it wants to keep hold of Gibraltar - or give it back.
James also roasted the MEP over his charity boxing match, which saw him lose to Lib Dem activist Toby White.
James accused Arnott of "embarrassing himself" and suggested UKIP can't get a thing right, no matter how hard the party tries.