Step 1: Conjugate a letter and a bug.
Step 2: Ask for the reason, with another letter.
Step 3: Pull the rest out of your shoe.
Step 4: Ignore the sea and replase it.
Extra tips below
The title will show you the answer.
Puzzling Stack Exchange is a question and answer site for those who create, solve, and study puzzles. It only takes a minute to sign up.
Sign up to join this communityStep 1: Conjugate a letter and a bug.
Step 2: Ask for the reason, with another letter.
Step 3: Pull the rest out of your shoe.
Step 4: Ignore the sea and replase it.
Extra tips below
The title will show you the answer.
Are you
AMYLASE?
Step 1: Conjugate a letter and a bug.
Conjugating Be (B/Bee) gives you AM.
Step 2: Ask for the reason, with another letter.
As @nikki found, you need to ask Y (why).
Step 3: Pull the rest out of your shoe.
As @nikki found, the shoe part is your LACE.
Step 4: Ignore the sea and replase it.
We need to ignore the C and replace it with an S, giving LASE.
Putting this all together we get
AM + Y + LASE = AMYLASE, an enzyme found in saliva (hence the title Spit it Out!)
Partial answer
Step 1: Conjugate a letter and a bug.
B (bee)
Step 2: Ask for the reason, with another letter.
Y (why)
Step 3: Pull the rest out of your shoe.
Lace?
Step 4: Ignore the sea and replase it.
Replace 'c' in lace with something?
So the answer is
bylane?