Fredo needs Mike's help to order a Banana Daiquiri at the Havana cafe. But wouldn't a Havana club-goer(i.e Fredo) know how to order his favorite drink??

I think the whole bit was a ploy by Fredo to keep Mike from suspecting that he and Johnny were in cahoots.


(Maybe Freddie inherited a bit of his old man's 'Sicilian Cunning' after all. )

Welcome Frank!
I believe we had a thread on this subject not long ago. I think we speculated that, as a Mickey Mouse nightclub operator, whoremaster and general Vegas lounge lizard, Fredo had to have visited Havana earlier--just as did millions of American tourists with less-prurient interests before Castro took over. In fact, Fredo said, "Havana's my kind of town," indicating that he had been there before.
But, I think the issue in that case was not that Fredo denied being in Havana previously, but that he denied knowing Roth and Ola--which was the source of Michael's quizzical look when he mentioned their names. Some of us here believe Michael was testing Fredo at that point.
As for the banana daquiri: Of course he should have known how to pronounce it, whether or not he'd been in Havana previously. IMO, it was another example of FFC making Fredo out to be terminally stupid, rather than an attempt by Fredo to mislead Michael.

I think it was more like Fredo trying to mislead Michael but not having the smahts to do it right, so he plays dumb about banana daquris.

I never thought of this as Fredo being deceitful, or as FFC trying to make Fredo unreasonably stupid.

Rather, Fredo's in a great deal of turmoil at that point. He's scared and regretful about his betrayal and he's realizing that he and Michael have more in common than he thought.

I think that he's just generally flustered and - never the sharpest knife in the drawer - simply blanks on the word.

I think it was just FFC's way illustrating Fredo's naivete and his dependence on Michael for so much.

FFC/Puzo might like a story like that..they might, they just might.

I think it was just one more scene showing Fredo being inept. Also it seems as if every scene with Fredo he is either treated with no respect or as if he’s invisible. During the hit on Vito the two shooters were so unimpressed at the sight of Fredo with a gun, that they didn’t even look his way. I’m sure Solozzo would have told them not to harm Fredo if he was there because there was going to be enough bad blood with just Vito getting whacked. In GF II, while Frankie is happy to see Fredo, Willie Cicci seems pretty dismissive of Fredo. We never see any scene where Clemenza or Tessio acknowledge Fredo as someone important and deserving any notice. Moe Greene slaps him around. Tom treats him like he’s not there. Its no wonder that Fredo is upset during the boathouse scene with Michael when he says that he wants to be treated with respect.

Actually, I think it is as simple as Fredo wanting to speak Spanish and order the banana daiquiri in Spanish, but he didn't know the word for banana, which is platino. Of course Mike didn't know the word either, so they both had a laugh when Mike answered the question in English. Of course the waiter understood the English phrase since many of his customers were Americans.

I think it should also be noted in that scene that Mike only had a club soda. Someone correct me if I am wrong, but I don't there were any scenes showing Mike drinking adult beverages.

There are very few. I think he had a glass of wine at Connie's wedding, and he had at least one "champagne cocktail" in the presence of Pentangeli. I also think he may have had a glass of wine during the "cent' anni" toast. Mike was a diabetic and probably could not handle alcohol.