How should I decorate this cake?

[StarsUponThars]

Okay, I need to decorate an M+S slicing bar cake (so pre-iced with flat white icing) in a jolly way for a relative's birthday. I thought that DS could help, and therefore that any quirkiness in decorating would automatically be forgiven .

I have little previous experience, but I can be crafty when needed. Does anyone have any ideas?

If it was me I'd be letting DS decorate to jis hearts content just provide him with neccessary icing & sweets...
or using skewers/toothpicks with paper hearts, flowers other shapes stuck in the top & icing around.
Cutting sweet necklaces & stringing between 2 skewers majes effective garland.
If its for female cutting heads off couple of nice artificial flowers & putting in one corner & candles in other.
For a kid cheap plastic charms/toys make effective docorations use toothpicks with triangles glued on like flags & write happy birthday

Hope others give you some suggestions but maybe give an idea of gender, age, relation to get more specific ideas

Thanks shabbie - it's for DS's grandad, 70 .