In Africa during WWI, a gin-swilling riverboat captain is persuaded by a strait-laced missionary to use his boat to attack an enemy warship.

Charlie Allnut: What are you being so mean for, Miss? A man takes a drop too much once in a while, it's only human nature.
Rose Sayer: Nature, Mr. Allnut, is what we are put in this world to rise above.
Charlie: We can't do that!
Rose: How do you know? You never tried it.
Charlie: Well, yeah, but I never tried shooting myself in the head neither.
Charlie Allnut: [exasperated and angry] Well I ain't sorry for you no more, ya crazy, psalm-singing, skinny old maid!
Charlie Allnut: Nobody in Africa, but yours truly, can get a good head of steam on the old African Queen.
Captain of Louisa: By the authority granted to me by his Imperial Majestey Kaiser Wilhelm the Second I pronounce you man and wife - proceed with the execution.
Captain of Louisa: [Annoyed with Charlie and Rosie] I think I shall have to hang you twice.
Charlie Allnut: One thing in the world I hate: leeches. Filthy little devils.
Rose: Dear?... Dear?... What is your first name?
Charlie Allnut: You know why did the chicken cross the road.
Rose Sayer: [missing the joke] I beg your pardon.
Charlie Allnut: Nevermind, miss.
Charlie Allnut: Nothin' a man can't do if he sets his mind to it. Never say die. That's my motto!
Charlie Allnut: There ain't nothing so complicated as the inside of a torpedo.
Charlie Allnut: [skitting Rose] Can you make a torpedo? Well do so Mr. Allnut.
Charlie: It's a great thing to have a lady aboard with clean habits. It sets the man a good example. A man alone, he gets to living like a hog.
[repeated line]
Rose Sayer: Mr. Allnut?
Charlie Allnut: Yes, miss.
Rose Sayer: Mr. Allnut! Mr. Allnut, you may come in out of the rain!
Charlie Allnut: I don't know why the Germans would want this God-forsaken place.
Rose Sayer: God has not forsaken this place, Mr. Allnut, as my brother's presence here bears witness.
Rose Sayer: Who do you think you are ordering me about?
Charlie Allnut: I'm the captain, that's what!
Rose: [after Charlie checks the boat for damage after going down a rather rough set of rapids] Could you see anything, dear?
Charlie Allnut: Yeah. The shaft's twisted like a corkscrew and there's a blade gone off the prop.
Rose: We'll have to mend it, then.
Charlie Allnut: Let's go while the going's good.
Rose Sayer: Fancy me a heroine.
Charlie: All this fool talk about The Louisa. Goin' down the river...
Rose: What do you mean?
Charlie: I mean we ain't goin' to do nothin' of the sort.
Rose: Why, of course we're going! What an absurd idea!
Charlie: What an absurd idea! What an absurd idea! Lady, I may be a born fool, but you got ten absurd ideas to my one, an' don't you forget it!
Rose Sayer: Dear Lord, We've come to the end of our journey, and in a little while we'll stand before you. I pray for you to be merciful. Judge us not for our weaknesses, but for our love and open the doors of heaven for Charlie and me.
Charlie Allnut: [about the grinking water they'll get from the engine's radiator] OGf course, it'll taste a little rusty, but we can't have everything, can we?
Charlie Allnut: How'd you like it?
Rose Sayer: Like it?
Charlie Allnut: White water rapids!
Rose Sayer: I never dreamed...
Charlie Allnut: I don't blame you for being scared - not one bit. Nobody with good sense ain't scared of white water...
Rose Sayer: I never dreamed that any mere physical experience could be so stimulating!
Charlie Allnut: [his stomach is growling] Ain't a thing I can do about it.
Rose: [as Charlie tries to stop her from revealing their plan] Oh stop it, Charlie, we've been through all that. I'm certainly not going to outlive you and that's all there is to it!
Charlie Allnut: What a time we had Rosie, what a time we had.
Rose Sayer: [after travelling through the rapids] Now that I've had a taste of it I don't wonder why you love boating.