[flacon]

Don't say "The position didn't work out", which would cause suspicion and make you look bad.

Blame them (Flaky Corp) for acting unprofessional.

Go into your current manager, tell them you are in a really difficult and awkward situation. That you have had some communications very recently that have made you very uncomfortable with the new company and made you reconsider your decision.

Your Boss will understand that messed up stuff happens sometimes and will want to avoid interviewing for the position. Tell your Boss you honestly do not want to leave the company now given this situation and that you want your old job back.

Value yourself and take charge of the situation. Dont just allow an awkward ego-feeling or unprofessional behavior by Flaky Corp to own you!

[hga]

In general I agree except don't lie!. Whatever reason would he have to not say "my offer was rescinded by Flaky Corp" and he can use that as an opportunity to praise the stability of his Fortune 500 company and that sector.