(Strip Number 183, Original Publication Date, 14 October 1981)
Panel 1: Having established that he's looking for kids to play with, Space Trooper Seven (Gordon) reports for duty; Mike welcomes him by showing him the secret handshake.
Panel 2: Lawrence objects to that by saying "NO, Mike! That's OUR Secret Salute! Yours an'MINE!"
Panel 3: He then goes on to deliver an ultimatum that draws its source from Lynn's inability to see that befriending one person does not mean the rejection of another; to be specific, he's WARNING Mike. Does he want to be best friends with him or NOT.
Panel 4: We next see Lawrence with his eyes bulged out in the Bug-Eyed Glare of Existential Horror thought-bubbling "NOT!" as Mike teaches Gordo the secret salute.
Summary: Back then, this was a meaningless little playground scuffle set into motion because a little boy who wasn't getting enough attention at home (because his mommy was dating Leisure Suit Teddy) thought that Mike was trying to ditch him too. The problem is that we have all this history that bears out Lawrence's fleeting suspicion that he was being replaced.