Celebrity endorsements are a funny business: George Foreman and his Lean Mean Grilling Machine; Shaquille O’Neal in the SEGA Megadrive classic Shaq-Fu; 50 Cent’s gangster Vitamin Water. There have been some truly bizarre ones over the years.

Now it seems as if celebrity-endorsed smartphone apps have become the done thing, with Newcastle defender Danny Simpson the latest to announce his own: a platformer entitled 'Danny Boy'.

How odd, we thought. But after doing a bit of research, we realised that Danny’s game was not even the weirdest iPhone app out there with a famous person's name on it. Oh no. Here's the top five we came across on our App Store travels...

1. Robbie Williams Racing
What’s the best thing to do when you’re a über-rich, mega-famous popstar who has managed to reignite his career by returning to the band that got him where he was? Make a terrible iPhone app, that's what. One which features yourself riding around a track on a motorbike, obviously.

Click here to purchase

2. Noel Edmonds' Cosmic Ordering
So Noel Edmonds got his job at Deal Or No Deal through cosmic ordering, apparently. If you want to follow in Noel’s footsteps and present a quiz show which makes even less sense than cosmic ordering, then this one is definitely for you.

Click here to purchase

3. I Am T-Pain
Ever wanted to be T-Pain? Of course you have. Think of the women, the money, the... boats? Unfortunately, this app doesn’t actually make you T-Pain - but it does make your voice sound like a gangster rapper, which is actually pretty cool.

Click here to purchase

4. Chuck Norris: Bring On The Pain
The whole Chuck Norris thing kind of died out a while ago, but that doesn’t mean his app is as bad as the non-sensical facts about him that used to get banded around. Oh, and did we mention that Chuck Norris doesn’t endorse apps? Apps endorse him. We’ll get our coat...

Click here to purchase

5. Danny Boy
Man United reject Danny Simpson’s very own app is set to hit the app store any day now, at the low, low cost of just £1.99. It features Danny jumping on platforms whilst juggling a football. It looks awful.

Have you seen any weirder celebrity-endorsed iPhone apps? Will you be purchasing 'Danny Boy'? Let us know on Twitter or Facebook!