A couple days ago Littlest said "boop" to Mommy. When Mommy repeated the sound to him he giggled and recognized it as his little word. So now we can say "boop" to him at any time and it instantly makes him thrilled. He even joins in and tries to say it back to us. It's so fun to be able to "talk" with him!
Also, about 4 days ago he just started sitting up. It's a cool new trick Daddy's been demonstrating to anybody and everybody. Go Dude!