Friends? I have no muggle friends! Well I guess I do if you count another muggle-born wizard...

I conjecture the next person loves everything shiny

Shiny things are very interesting. Sometimes, they're shiny enough to act as a mirror!

I conjecture the next person prefers chocolate to vanilla!

I reckon? Sweets aren't my favourite.

I conjecture the next person is really fascinated by muggle science!

It's cool, but not nearly as cool as magic!

I conjecture the next person is a phenomenal swimmer!

Nope, just a good swimmer.

I conjecture that the next person finds reincarnation to be really cool

It's a pretty cool concept, but it depends on what type we're talking about. Some people believe spirits wander to find where they are to be reincarnated next, some believe a higher being chooses, while others believe it is random, or based on the deeds you did in a past life.

I conjecture the next person hates raisins, especially in cookies.

I don't like raisins by themselves, but I like them in something like toast

I conjecture that the next person is below 4'7 *cries*

Nope, I'm 4'11.

I conjecture that the next person knows what a Demiguise is.

A what? Sorry, I don't know too much about magical creatures
OOC: I have a model of one in a little chirstmas themed display box! It sits on my bookshelf guarding my books!
I conjecture the next person likes bats!

Yup!

I conjecture the next person has a big secret!