Allmusic.com says this was written by Boudleaux Bryant and Little Jimmy Dickens:

Copied from http://www.ibiblio.org/bawdy/ballads/silly.html:

IT MAY BE SILLY (BUT AIN'T IT FUN)
As sung by Sid "Hardrock" Gunther

1. I used to think that makin' love was foolish as could be
But when I hit the age of twelve a little girl told me
"Just kiss me once and if you don't like it then I'll go away"
When I give up her arrow this was all that I could say:

CHORUS: It may be silly, but ain't it fun
It beats pitcher shows and carnivals all rolled up into one
You hug a while then you kiss a while and say, "I love ya hon"
It may be silly, but ain't it fun.

2. No matter if it's ten below or ninety in the shade
I'm always set and ready when there's lovin' to be made
My heart is just as frisky as a little ol' poodle pup
So if you're ready for a kiss, well I've got one a-comin' up. CHORUS

3. One day I took my sweetie on a visit to the zoo
A monkey and his lady friend were busy a-pitchin' woo
He bit her on the ear and then he grinned a silly grin
I knew what he was a-thinkin' as she smacked him on the chin. CHORUS