|The better suggestion is to avoid situations where you misrepresent yourself in front of management. You were very kind, and maybe a little foolish, to try this once. The fact that the suggestion bombed most likely indicates that it was marginal, regardless of the presenter. |
From the very start, this was a huge no-win for you. If that first suggestion had been a major winner, there is not much likelihood that your friend would have sat quietly and let you reap the glory. One way or another, the truth would have come out, and you would have looked rather foolish. At the same time, since the suggestion fell flat, you still looked rather foolish.
Tell your friend that you are not going to do this again, but also let him know that you would like to hear some of his other suggestions and work with him to fine-tune the best one or two for him to present. It sounds like your friend has a bushel of suggestions, and he may be confusing quantity with quality. As a quality friend, you can help him separate the wheat from the chaff.