Only Fools and Horses, Series 7 (1990-1991)

Denzil:
[exasperated about Del being secretive] How can we be certain that this stuff [indicates the barrels containing the substance] isn't dangerous?!

Del:
[equally exasperated about Denzil's supposed insubordination] Because it is not! And that's the truth! [he goes into the shed, closing the door behind him]

Trigger:
There you are, you've heard it from the horse's mouth, now. You get that end... [moves to pick up one of the barrels]

Denzil:
What d'ya mean, I've heard it from the horse's mouth?! That's Derek Trotter in there, not bloody Einstein!

Trigger:
Del knows what he's talking about. And I don't see what the Beatles' manager's got to do with it anyway.

Denzil:
[frustrated] But Trig... [thinks on what Trigger has just said] What?!

Trigger:
When we was at school, Del was the best in our class at chemistry. He used to sell homemade fireworks. He even blew up the science lab once.

Denzil:
[angry] Yes, I remember! I was doing detention in there at the time!

Trigger:
And you say he don't know what he's talking about?

Denzil:
[annoyed] Right, that's it, Del! I am not touching them! I'm off!

Del:
[still in the shed, therefore unseen] Denzil, now, believe me, it's harmless! And to prove it, I'm gonna help you carry it! Well, I can't play fairer than that, can I?

Trigger:
Look, it can't be dangerous, Denzil.

Denzil:
How can you be sure?!

Trigger:
Cause Del's just offered to help us carry 'em.