What are some simple reality checks I can perform?

I'm trying to make it a habit to do reality checks whenever I can. The quickest and most discrete thing I thought of was to just stop and look at my hands. The thing is, it doesn't feel like enough. I saw a post a while back about someone who looked down and noticed his hands had turn into claws, but what are the odds I'll have the same experience? Are there any small reality checks you do that are easy to make a habit out of? I've heard of the old look at a digital watch and then look again - has anyone gone lucid from that?

Edit: I feel noobish. I just found the reality check tutorial. Well, I guess the question is still relevant - what do you use as a reality check, and when?

The easiest and the most reliable RC to me, would be pinching my nose and see if I could breathe, and it worked wonders. There are others, like looking at a digital watch and see if the time changed. Read something, then read it again, notice any difference?

For all I know, there are infinite amount of Reality Checks.

The looking at hands one isn't simple, you could write in your hand something like "Plug your nose" or "RC" and it will get better!
And I use gravity as a RC.

Pinching your nose isn't very discreet.

The digital clock one has been very promising for me. I've gotten some of my lucids using this reality check and one time I had a dream that I looked at my clock and it was basically just like the one in my signature. It doesn't make sense, you notice, bam you're lucid. It's also discreet.

Looking at your hands can just help remind you of what your goal is. You're in a dream, you look at your hands, and you're suddenly lucid. Some people will count their fingers to see if they still have 5. I count this as being discreet too (if you make it).

Another one is trying to remember how you got where you are. If you can't remember, you're probably dreaming. Also asking critical questions such as "why am I here", "who am I?", "does this make sense"?

:)

You can make the nose pinch discreet by carrying a tissue with and pretending you're blowing your nose.