The Blink-182 drummer stepped in Dave Grohl's shoes as he performed 20 songs by the grunge pioneers with the 'Circles' hitmaker on lead vocals last month, and they managed to raise over $500,000 for the United Nations Foundation's COVID-19 Solidarity Response Fund for the World Health Organisation.
And Travis has revealed that the pair are jamming and penning some new material together.
Asked if they are collaborating on anything else, the 'I Miss You' sticksman said: ''Yeah, I'm actually talking to you from my bus.
''I'm going up to Salt Lake to just write for a week with him.
''Just jam and have fun.
''I went up there the day before and we went through the set one time. ''Then the next day we went through the set one time and we just played it.
''You can't over-rehearse Nirvana songs or it loses its vibe.
''So the whole vibe over there has been very relaxed and just whatever happens happens.''
Travis - who has recently been collaborating with Machine Gun Kelly on his pop punk record, Tickets To My Downfall' - also admitted that he thought it was a joke when he was asked to learn 20 Nirvana covers in a matter of days for the live-stream.
He added to SPIN: ''And I honestly thought he was joking 'cause the idea of driving to Salt Lake City, 'Really, are we gonna learn 20 Nirvana covers and really are we gonna figure out a way to live stream it?'
''So I was like, 'I'd love to, I love Post and I love you, so just tell me if it's actually serious.'
''We kept talking about it and they said they were serious and I should come out there in three days.
So I was like, 'Whoa, this is really happening.'
''So I just spent the next three days learning 20 Nirvana songs, which was fun because Nirvana is one of the greatest bands of all time.
''And then just driving out there and doing that quarantine was so cool when people are sitting around and really need live music. And what better band to pay tribute to than Nirvana?''
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