Cramer's lightning round: Sell BlackBerry

• It's that time again! "Mad Money" host Jim Cramer rings the lightning round bell, which means he's giving his answers to callers' stock questions at rapid speed.

BlackBerry: Sell.

Fuelcell Energy: "Fuelcell is not as good as Plug [Power]. ... but what matters is they have enough money to be able to get it to where [green] hydrogen fuel ... can be a legitimate fuel, and nobody else really does."

Opendoor Technologies: "I think you've got a good one and I am not going against it."

American Superconductor: "American Superconductor is going to work if this continued movement toward speculation stays strong."

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