John Stamos brought his 'most beautiful' baby boy to 'Kimmel' for Halloween

John Stamos is one proud papa!

The "Fuller House" star proved that Wednesday night when paid a visit to "Jimmy Kimmel Live" and brought his 6-month-old son along to celebrate little Billy's very first Halloween.

"Isn't he just the most beautiful baby?" Stamos raved after wife Caitlin McHugh delivered the wee one to the stage.

Kimmel couldn't argue that point, saying, "This is the cutest baby I've ever seen. You gotta make more of these!"

And Billy was even more adorable than usual thanks to an amazing costume his mom made.

In honor of the night's 1970s retro costume theme, host Kimmel dressed up as the title star from "Welcome Back, Kotter" and Stamos went as student Vinnie Babarino. But Billy stood out as another small-screen character from the decade in a red and silver Mork from Ork jumpsuit.

"I'm so in love," the 55-year-old father said as he gave his boy a kiss.

Give appropriate praise. Instead of simply saying, "You're great," try to be specific about what your child did to deserve the positive feedback. You might say, "Waiting until I was off the phone to ask for cookies was hard, and I really liked your patience."

And not just with his baby.

Stamos also gushed about his bride.

"I'm so grateful and happy," he said of her and their marriage.