That color you're wearing really washes you out--I'm just saying...
Your son has never amounted to anything in all of his thirty years--I'm just saying...
A certain person from my way-distant past (okay, it's my ex-husband's mother) wins the prize for best usage. She sprinkled it liberally throughout her conversations. Your butt sure does look wide in that outfit--I'm just saying... You're going to cook a Thanksgiving turkey?? You??--I'm just saying...
It can also be tacked on to a nice little bit of gossip. But that only works if:
1) the gossip might not be true, but it's too good not to share.
2) the gossip is about someone in your circle of friends/acquaintances.
That way the conversation becomes so much more interesting. She looks like the type that would cheat on her husband then becomes I think she cheats on her husband--I'm just saying...
Or (another nice possibility): She looks like she could have had some plastic surgery can then become she probably had a (insert type of plastic surgery here) job--I'm just saying...
My husband pointed out to me that in the Navy, there was a handy little phrase often used. If you prefaced an insult with with all due respect, you were allowed to say pretty much anything.
Armed with those two all-purpose phrases, everyone can respectfully skate into the new year guilt-free...I'm just saying...