Dad duty calls! Chris Pratt inadvertently showed off a sweet note from his son Jack, 9, when snapping a shirtless selfie from set for Instagram on Monday.

“See ya at 8:00 ish,” the yellow sticky note reads, signed with a heart and his name.

READ MORE: Chris Pratt Closes the Door on Indiana Jones Casting Speculation After Getting 'Scared' by Harrison Ford

The brief memo was stuck on a mirror in what appears to be Pratt’s on-set trailer, where he’s filming Prime Video’s “The Terminal List”. In the snapshot, Pratt shows off his abs and a faux wound on his collarbone with the cheeky caption, “Lookin’ cut.”

Pratt’s brother-in-law Patrick Schwarzenegger was quick to spot the photo’s neon-coloured easter egg, commenting, “See yah at 8 ish jackkkooo,” while countless fans also referenced the note in their reactions.

Pratt shares his eldest child with ex-wife Anna Faris. He is also a doting father to two daughters, 1-year-old Lyla and 1-month-old Eloise, with wife Katherine Schwarzenegger.

In an interview with ET at the premiere of his new action series, Pratt said that Jack “does a great job as a big brother.”

READ MORE: Chris Pratt Says He Cried When He Got Backlash Over 'Healthy Daughter' Comments

“There’s a big age separation… [and] he does a great job, he’s so sweet with them,” Pratt marveled. “And they love him so much and they miss him when he’s gone.”

Aside from starring in “The Terminal List”, Pratt is also stepping behind the camera into the role of executive producer. For more on the project, watch below.

More From ET: 

Kelly Rowland Is ‘Livid’ Over Sesame Place Viral Video: ‘I Would’ve Burned the Place Down’ (Exclusive)

Jennifer Lopez’s Mom Lupe Rodríguez Calls Ben Affleck Her Daughter’s ‘True Love,’ Says Sunny Hostin

Frankie Jonas Admits He Was Star Struck When First Meeting Brother Joe Jonas’ Wife Sophie Turner