Spoonerism
The other kind of error is the spoonerism--an unintentional transposition of sounds.
From Mirriam-Webster: "The name comes from a British clergyman and educator named William Archibald Spooner. And apparently, he just naturally came up with spoonerisms very, very frequently, and it seems, was constantly speaking to audiences. And so there are all these anecdotes about him just saying absolutely ludicrous things. There was a time when he was giving a speech and Queen Victoria was in the audience and he said, apparently, 'I have in my bosom a half-warmed fish,' when he actually intended, 'I have in my bosom a half-formed wish.'"
My favorite from recent talk radio: that famous write-in candidate "Maxine Vandate". Think about it...
Some others:
"Three cheers for our queer old dean!" (while giving a toast at a dinner, which Queen Victoria was also attending)
"Is it kisstomary to cuss the bride?" (as opposed to "customary to kiss")
"The Lord is a shoving leopard." (instead of "a loving shepherd")
"A blushing crow." ("crushing blow")
"A well-boiled icicle" ("well-oiled bicycle")