Peter and Remus bringing soda cans onto the train in 3rd year after realizing how unaware of muggle stuff James and Sirius are and convince them to shake the cans otherwise the "flavors won't mix."

Remus and Peter bringing those cheap finger traps in fourth year and James and Sirius have to be taken to Madam Pomfrey to get them taken off.

Peter and Remus constantly pranking Sirius and James with muggle things.