OK, I had lots of less interesting things nothing better to do today so here's We're Going On A Wolf Run. Apologies to Michael Rosen and Helen Oxenbury, and for the swearing. Feel free to improve on it 
We’re going on a Wolf Run!
It’s going to be a tough one…
What a beautiful day!
We’re not scared (speak for yourself, I'm shitting me breeks).
Uh-oh! Tyres. Big bouncy tyres.
We can’t go under them
We can’t go round them
Oh no! We’ll have to go over them!
Bounce trip bounce trip bounce trip
We’re going on a Wolf Run!
It’s going to be a tough one…
What a beautiful day!
We’re not scared (yeah, right).
Uh-oh! Mud. Thick, squelchy mud.
We can’t go over it
We can’t go under it
Oh no! We’ll have to go through it!
Squelch squerch argh my knee squelch squerch
We’re going on a Wolf Run!
It’s going to be a tough one…
What a beautiful day!
We’re not scared (actually, not any more).
Uh-oh! A lake. A big, cold lake.
We can’t go under it
We can’t go round it
Oh no! We’ll have to go through it!
Swim splash ooooh it’s cold swim splash oh shit cramp
We’re going on a Wolf Run!
It’s going to be a tough one…
What a beautiful day!
We’re not scared (but we’re very wet and muddy).
Uh-oh! More mud. GOTO verse 4…
We’re going on a Wolf Run!
It’s going to be a tough one…
What a beautiful day!
We’re not scared (in fact we’re having a ball).
Uh-oh! Monkey bars. Swingy tall monkey bars.
We can’t go over them
We can’t go round them (hell yes we can – see you the other side).
We’re going on a Wolf Run!
It’s going to be a tough one…
What a beautiful day!
We’re not scared (this is FUN!)
Uh-oh! More fecking mud. More sticky, smelly mud.
We can’t go over it
We can’t go under it
Oh no! We’ll have to go through it!
Squelch squerch bugger squelch squerch arse
We’re going on a Wolf Run!
It’s going to be a tough one…
What a beautiful day!
We’re not scared (but getting a bit tired)
Uh-oh! A slide. A really long, muddy slide.
We can’t go round it
We can’t go over it
Oh no! We’ll have to go down it – head first!
AAAAAAAAARRRRGHHHHHHHHH!
We’re going on a Wolf Run!
It’s going to be a tough one…
What a beautiful day!
We’re not scared (but getting really quite knackered now and I’ve got muddy water up my sinuses)
What’s that? One 8km marker. Only 2 more to go!
On through the sodding mud!
Squelch squerch squelch squerch I hope I never see mud again
On up the hill!
Puff pant puff pant puff pant
On over the hay bales!
Scrabble shove scrabble shove
On over the wall!
Scramble scramble actually I’ll just sneak round this one
Get to the finish!
Jump in the mud pool!
Smile for the camera.
SPLASH. Done. I need a beer.
Same time next year?