The Office Workout

This workout utilizes an exercise band, also commonly called a Thera-Band (this is only one brand name of many similar styles of products). You can purchase these at online retailers, such as Amazon, and they are relatively inexpensive. Many come with suggested exercise routines, as well. I bought mine at Big 5 Sporting Goods several years ago, for under ten dollars. 

(If you need links to demonstrations of the various exercises below, feel free to comment and I will post the links as a reply.)

For each item, complete three sets of ten reps, or until you spot the next item on the list in the episode, whichever comes first:

Arms:

Dwight and Angela have a secret meeting:

Bicep curls: two sets full, single set partial curl 

(Carrie Dorr has a great demo of the partial bicep curls in the "Studio Series: 1" video of the Pure Barre video series; all exercises will be using a Thera-Band in this workout, unless otherwise noted)

Michael demonstrates his social ineptitude:

Tricep extensions

Close up or interview with Stanley:

Bent row (as demonstrated here)

Michael disses Toby:

Lying pullover (also from the same article, which highlights various resistance band exercises, found here)

Dwight talks about his farm:

Reverse flye (from this workout video)

Pam and Jim exchange looks:

Resisted pushup (from this site, but also in the short video, linked above)

Legs:

Jim plays a prank on Dwight:

Prone leg curls, three sets each side

(Double-time speed if the prank involves Jell-o gelatin)

Jim makes his classic look (above) towards the camera after another character makes a statement:

Standing adductor, three sets each side

(this is the Thera-Band version of the "Inner Thigh Press" from The Big Bang Theory Workout; add tension by looping the of the ends of the Thera-Band around your ankle or arch of your foot and creating light tension)

Michael hits on a woman:

Ankle flexion, full range of motion, three sets each side

Jan shows up:

Side lunge/squats (as shown in this handy .gif here), three sets each side

Any of Michael's girlfriends or ex-girlfriends make an appearance:

Rotating lunge and row (found here)

Abs:

Andy is referred to (or refers to himself) as "Nard Dog":

Plank for 1.5 mins each rep

Erin's voice sounds perky or chipper:

Standard crunch

Cecilia Halpert is mentioned or makes an appearance:

Reverse crunch

Kelly or Michael harass Ryan:

Bicycle crunch

An interesting conversation takes place at the vending machine:

V-sits

Full body:

Any time Michael references gender, sexuality, race, etc.:
Squat with overhead press (there is a great illustration of this exercise here)

Michael mentions Jan's fake boobs:
Side lunge with side raise (found on the same site as the previous exercise)

Dwight attempts to one-up Michael:
Horse stance cross (from this webpage)

Steve Carell (Michael) wrote or directed the episode:
Monster walk, three sets each side (found here)

B.J. Novak (Ryan) wrote or directed the episode:

Sliding plie squat pull (photos here)

You see Creed in the background of the scene, or he appears in an interview clip:

Bridge kick press (from the same site as above)

Phyllis reveals something embarrassing about Michael in high school:
Bow and arrow pull (from this video)

The Big Bang Theory Workout

This routine utilizes 5lb (or your current weight) dumbbells and your own body weight for the remainder of the exercises.

For each item, complete three sets of ten reps, or until you spot the next item on the list in the episode, whichever comes first:


Arms:
Sheldon knocks on Penny's door (e.g. Knock knock knock, Penny, repeat...):
Complete sets of arm circles with five pound dumbbells

Someone references a video game:
Chest press with five or ten pound dumbbells

Sheldon tells someone to get out of his spot or Sheldon sits in his spot:
Shoulder raises with five pounds

You see Penny sporting loungewear:
Narrow push-ups

The Guys eat at the Cheesecake Factory:
Wide push-ups

Someone mentions Star Trek or Star Wars:
Standard push-ups


Legs:
Sheldon wears his flash costume or green lantern tee shirt:
Plie squats

Sheldon says "I'm not crazy, my mother had me tested" or otherwise mentions mental health issues:
Squat jumps

Someone makes fun of the fact that Howard doesn't have his PhD:
Inner Thigh Press (this website calls it "Inner Thigh Attitude Pulse," on page 5 of 9)

Raj talks about India:
Side lunges

Raj's sister Priya shows up or someone mentions that she dated Leonard:
Standard lunges

Amy kisses Sheldon:
Side leg lifts (these are also known as Crescent Kicks from 4 of 9 on the same page as above)

Bernadette imitates Howard's mother:
Bridge for 1 min each rep


Abs:
Sheldon mentions trains:
Plank for 1 min each rep

Sheldon mentions some reference to Leonard or Penny possessing lower IQ:
Reverse crunch

Howard makes an inappropriate, uncomfortable or lewd comment:
Bicycle crunches

Howard mentions living with his mother:
Roll ups

Bernadette whines:
Toe reaches


Full body:
Penny, Amy or Sheldon sing Soft Kitty:
Criss cross jumping jacks (there is a good demo of this exercise here)

Someone mentions Steven Hawking or Howard impersonates Hawking:
Burpees (here is a demo of this exercise)